Next Article in Journal
Feeding Habit-Specific Heavy Metal Bioaccumulation and Health Risk Assessment of Fish in a Tropical Reservoir in Southern China
Previous Article in Journal
Use of Ensemble Model for Modeling the Larval Fish Habitats of Different Ecological Guilds in the Yangtze Estuary
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Fishes
Volume 8
Issue 4
10.3390/fishes8040210
fishes-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Experimental Mixed Gillnets Improve Catches of Narrow-Barred Spanish Mackerel (Scomberomorus commerson)

by
Luong Trong Nguyen
1,*,†,
Khanh Quoc Nguyen
1,2,† and
Toan Phi Nguyen
3,†
1
Institute of Marine Science and Fishing Technology, Nha Trang University, 2 Nguyen Dinh Chieu, Vinh Tho Ward, Nha Trang City 650000, Vietnam
2
Fisheries and Oceans Canada, St John’s, NL A1C 5X1, Canada
3
Research Institute for Marine Fisheries, 224 Le Lai, Ngo Quyen Ward, Hai Phong City 180000, Vietnam
*
Author to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Fishes 2023, 8(4), 210; https://doi.org/10.3390/fishes8040210
Submission received: 15 March 2023 / Revised: 12 April 2023 / Accepted: 13 April 2023 / Published: 18 April 2023
Browse Figures
Versions Notes

Abstract

:
A new gillnet made from multiple mesh sizes ranging from 125 to 180 mm of stretched mesh (experimental gillnet) was tested under commercial fishing conditions to compare the fishing performance with that of conventional gillnets with a 125 mm mesh opening (control gillnet). Catch efficiency and size selectivity between the two gillnet types were evaluated throughout one year of fishing in three different locations in the waters of Vietnam. Experimental gillnets caught narrow-barred Spanish mackerel (Scomberomorus commerson), spotted mackerel (Scomberomorus guttatus), and wahoo (Acanthocybium solandri) in comparable amounts to the control gillnets, with the moon phase, month, and depth explaining some of the variation in the catch per unit effort (CPUE). An analysis of the size-dependent catch comparison rates and selectivity parameters showed that the experimental gillnets captured a wider range of narrow-barred Spanish mackerel sizes, but with a substantial proportion of individuals larger than those caught by the control gillnets. This is of higher weight per unit effort, and fishing enterprises therefore could improve their economic benefits by using modified gillnets with multiple mesh sizes. Our findings also support the biological and environmental benefits of the modified gillnet size selection, which might also extend to other species.
Keywords:
mesh size; seasonal effect; moon phase; Vietnamese fisheries; catch comparison
Key Contribution: Experimental mixed gillnet capture the same amounts as the traditional gillnets, but catch larger size fishes, resulting in increasing the weight per unit effort and thus improve the economic benefits for the fishing enterprises, as well as contributing to the maintenance of the narrow-barred Spanish mackerel stock.

1. Introduction

Gillnets have wall net configurations and are a passive stationary fishing gear, where capture depends on fish actively having physical contact with the gear during their natural diel movement, foraging movement, or seasonal migration [1]. Gillnets are one of the most commonly used fishing gears in the world, harvesting multiple species by commercial and artisanal fleets in both inland and marine capture fisheries [2,3]. In some fisheries, gillnets are considered an essential component for the maintenance of especially coastal fisheries, local value chains, and employment systems in fisheries-dependent areas because of the low initial cost and operational cost to commercial fisheries, contributing to the extension of the fishing season [4]. However, despite the popularity of gillnet fisheries, there is the potential for a low-quality fish catch if the nets soak for long periods in the water [5]. Like other fishing gears, gillnets are not 100% selective for the target species [6,7], and they also catch unwanted bycatch species, such as seabirds, sea turtles, and marine mammals [8,9,10,11]. “Ghost fishing” produced by lost, abandoned, and/or discarded gillnets, which is the continuous catching of target and nontarget species, represents another impact of gillnets on the marine environment and ecosystem [3,4,12]. To promote sustainable harvesting, ideal gillnets would fish across appropriate spatiotemporal scales that maximize catches of the permitted species and eliminate unwanted species and sizes.
The narrow-barred Spanish mackerel (Scomberomorus commerson) is an epipelagic species belonging to the family Scombridae and is distributed throughout the tropical-temperate Indo–Pacific [13,14,15]. The species can weigh as much as 70 kg at a 240 cm fork length (FL) and live about 22 years [16]. The global landings of narrow-barred Spanish mackerel have increased from 83,324 t in 1980 to >294,997 t in 2020 [17]. In Vietnam, various kinds of fishing gears are used, such as set-net [13], purse seine [18], and stick-held falling net [19], but most of the total catch is harvested using gillnets [20,21]. The narrow-barred Spanish mackerel resource is exploited year-round with 10 days break each month (typically from the 11th to 19th of the lunar month) to avoid low catch rates during the full moon phases on fishing grounds within 150 m depth [22,23,24,25]. In 2021, landings in Vietnam were 36,000 t accounting for USD 12.5 million in landed value. However, the resource of the narrow-barred Spanish mackerel has shown a sign of decline as revealed by catch rates of key fisheries decreasing over time [13,21,22,23,26]. The sizes of narrow-barred Spanish mackerel caught by Vietnamese gillnets typically range from 23.5 to 104 cm FL [22,24]. Increasing fish size selection through the use of larger mesh sizes could improve the ecological benefits and contribute to sustainable fisheries development [27,28,29].
Historically, Vietnamese fishers have used different lengths and heights of gillnets made of polyethylene (PE) or monofilament nylon with variable mesh sizes ranging from 61.2 to 200 mm with stretched mesh openings [23,24,30], which are deployed vertically in the water column by having weights along the bottom and floats along the top. As an important commercial species, several studies on catch rates and selectivities of gillnets targeting narrow-barred Spanish mackerel have been published [22,23,24,25], but these reports have failed to describe the spatiotemporal scales for the catch rate, size selectivity, and distribution of narrow-barred Spanish mackerel. The effects of environmental and biological factors that can influence the catch efficiency of gillnets have not been documented [31]. These are critical indices because a small change could affect the size selection and result in catch rate variations.
In addition to fish occurrence, density, mobility, and environmental conditions, which are considered critical factors for gillnet catch efficiency [1,15,32,33,34,35], technical factors, such as net length [1], hanging ratio [36], twine size and material [37,38], and mesh size, also affect catch rates [15,22]. The objective of the present study was to compare the catch rates and size selectivity of the control gillnets versus the new gear designed with mixed gillnets with larger mesh sizes across the entire fishing year in different locations incorporating various environmental and biological influences. In principle, larger mesh sizes could likely improve the capture sizes of the target species. However, they could also reduce catch rates, resulting in a negative impact on fishing efficiency and economic profits of fishing enterprises.

2. Materials and Methods

2.1. Data Collection

The comparative fishing experiments were conducted on board commercial fishing vessels (NĐ2790TS, NT0555TS, and BV94035TS) from 6 November 2008 to 30 October 2009 in the three different locations, namely the Gulf of Tonkin and center and south of Vietnam (Figure 1). Fishing locations in each study site were decided by the captain following traditional fishing practices. Both traditional gillnets, herein called control nets, and mixed gillnets, herein called experimental nets, were deployed and retrieved at the same time within each day and left at sea for the same period of time (soaking time) for comparative purposes (Figure 1). Control nets were constructed with 1.5 mm diameter dark green PE twine and had a 125 mm mesh opening size with a 0.59 hanging ratio (Figure 2). Experimental nets had similar configurations to those of the control nets, but with multiple mesh sizes ranging from 125 to 180 mm and variable hanging ratios (0.59–0.7) (see Figure 2 for details). Each gillnet consisted of 100 net webbings (sections), for a total length of 4500 m.
Gillnets were set in the seabed during the night. For each haul and deployment of gear, captains provided the date, time, soak time, sea depth, and location (coordinates). After each deployment, all individuals captured were separated by species level, counted, and recorded as the catch rate per gillnet by scientists. As the main target species, the total lengths of all narrow-barred Spanish mackerel caught by control gillnets and experimental gillnets were measured to the nearest mm using a measurement board. Other species were recorded in number, but the lengths were not measured.

2.2. Statistical Analysis

We prepared the data, conducted the analyses, and produced figures using R (V4.1.2) Statistical Software [39]. Generalised Additive Models (GAMs) were used to compare the catch per unit effort (CPUE) between the control gillnets and experimental gillnets, where the catch was calculated as the number of individuals caught per hour for each gear type, and effort was a section (net webbing) of gillnet. GAMs were used because the shape of the relationship between the response variable (CPUE) and predictor variables (moon phase, deployment month, and depth) was unknown. GAMs included smoothers, which are algorithms that attempt to generalize data into smooth curves by local fitting to subsections of the data [40]. We estimated the variation of CPUE, while including potentially confounding moon phases, time series, and depth variables. In this model, we incorporated the moon phase variable because the catch, as a factor in our analysis, was known to be influenced by lunar rhythm and natural light, which is typical for most pelagic fisheries [13,18,19,41]. Moon phase was a continuous variable ranging from 0 to 1 corresponding to the new moon and full moon, respectively. Fishing month and depth were also continuous variables. The candidate model was as follows:
Log(CPUE) = α + Trm + Loc + s(Moonphase) + s(month)+ s(depth) + ε
where α is the intercept; Trm is the experimental treatment (control gillnets vs. experimental gillnets); Loc is the fishing locations (Gulf of Tonkin, center, and south of Vietnam); s is a thin-plate smoothing spline function; and ε is an error term as defined above. Because of the potential nonlinear relationships of CPUE with moon phase and month, cyclic cubic regression spline smoothers were applied, which forces the response to have the same start- and endpoint that was handled to smooth the predictors. The depth variable was treated using a thin-plate smoothing spline with an automatic penalizing function that adopted zero values to exclude the effect of the independent variable from the model. We tested and found that the best model fit was produced using a gamma error structure with a link log. To obtain spatially relevant responses and to avoid overfitting the models [42,43], we set the number of knots for each of the smoothers to 4 (k = 4), allowing the smoother to divide the response from each explanatory variable into three parts. Models were visually inspected for spatial autocorrelation by plotting smoothed correlograms of model residuals, deviance residuals vs. linear plots, and deviance residuals vs. fitted plot [44]. Analyses were conducted separately for each species.
A generalized linear mixed-effect model (GLMM) was used to compare the length of the captures from the catch between treatments in each length class [45,46,47]. The logit catch proportion retained ((experimental/(experimental + control)]) of the catches-at-length was estimated by low-order polynomial GLMMs (i.e., constant, linear, quadratic, cubic, and quartic) to fit the proportions at each length class retained in experimental treatments. In this model, the logit of the retained catch proportion per length class was considered as a response variable, and length class was the explanatory variable, and the random effect was set on the intercept. A polynomial GLMM was applied to fit curves for the expected proportions of catch at a given length class using the glmer function from the lme4 package [48]. The best model fit was determined based on the minimum Akaike information criterion (AIC) using the function AICctab from the bblme package [49]. Our data were fit with a binomial distribution. We fit the following model:
logit(y) = α + β1 + β2 + β3 + β4 + b + ε
where y is the catch proportion retained between treatments as defined above. α is the intercept. β1–β4 is the modeled polynomial (i.e., linear, quadratic, cubic, and quartic) coefficients. b is a random factor (where b ∼ N [0, σ2]). ɛ is the error term. In this analysis, a proportion of 0.5 indicated no difference in catch between the two treatments at the given length, whereas a proportion greater than 0.5 indicated that more fish were captured by experimental gillnets than by control gillnets and vice versa. For example, if the catch proportion equaled 0.7, 70% of the analyzed species in the specific length class were captured by experimental gillnets and 30% by control gillnets, and if the proportion was 0.3, 30% of fish at given length class were caught by experimental gillnets and 70% by control gillnets. The significance between treatments was determined by confidence intervals (CIs); if the CIs overlap by 0.5, there is not any significant difference in catch-at-length between experimental and control gillnets at the given length class [45].

3. Results

Over the course of the study period (6 November 2008 to 30 October 2009), we conducted 67 nights of fishing and successfully deployed a total of 133 sets of nets (67 control net sets and 66 experimental sets). The fishing depths (mean ± 1 SD, in m) were 53.7 ± 5.1, 84.3 ± 17.8 m, and 66.7 ± 5.6 m for the Gulf of Tonkin, center, and south of Vietnam, respectively. The effective fishing time (i.e., time that gillnets deployed onto the sea bed) ranged from 2.2 to 11.8 h (mean of 6.9 h) for both types of nets. There was a variation of the soak time between seasons and locations due to the weather, fish abundance, and fishing habits.
As is usually the case in tropical fisheries, diverse groups of species were caught during the study. Control and experimental gillnets caught 27 and 28 species, respectively (Table 1). The main target species included narrow-barred Spanish mackerel (Scomberomorus commerson), spotted mackerel (Scomberomorus guttatus), and wahoo (Acanthocybium solandri). Together, these three species comprised 73.9% and 84.3% of the total catch of all species captured by the control and experimental gillnets (Table 1), and only these three species were included in the catch analysis. Length analysis was carried out on narrow-barred Spanish mackerel. Specifically, the control gillnets captured 55.7, 1.6, and 16.7%, while experimental gillnets captured 66.0, 1.6, and 16.8% narrow-barred Spanish mackerel, spotted mackerel, and wahoo, respectively (Table 1).
The models show that there were no significant differences in the CPUE between the control and experimental gillnets for the examined species. The modelled CPUE for narrow-barred Spanish mackerel, spotted mackerel, and wahoo for the control gillnets were 0.84, 0.02, and 0.27 individuals per gillnet, respectively, compared with 0.82, 0.01, and 0.06 individuals per gillnet per hour for those species caught in experimental gillnets, respectively (Figure 3). Additionally, the models detected significant differences in the CPUE of the total examined species between locations. The CPUE of narrow-barred Spanish mackerel was the highest in the south site (CPUE: 2.11), followed by the center site (CPUE: 0.84) and the Gulf of Tonkin (CPUE: 0.48), which was statistically significant for all pairwise comparisons (Figure 4). The CPUE of wahoo was also significantly higher in the south site (CPUE: 0.68) than in the center (CPUE: <0.01) and Gulf of Tonkin (0.04) sites (Figure 4). However, there was no significant difference in the CPUE of spotted mackerel among the locations, which had a low CPUE (Figure 4).
We tested different models to identify the best fit based on the selected criteria. The GAMs showed that the best explanation of the variations in the CPUE of the examined species included moonphase, month, and depth. The CPUE patterns were similar for all tested species (Figure 5). For example, the CPUE significantly decreased with the high lunar illumination levels for all species tested (Figure 5A–C). For all species, the CPUE peaked in September (Figure 5D–F). We observed a spatial variation, with peaks of CPUE at 90 m depth (Figure 5G–I).
The total length of narrow-barred Spanish mackerel caught by the control gillnets ranged from 370 to 1250 mm, compared with that of those caught by experimental gillnets ranging from 370 to 1760 mm (Figure 6A). Most of the fish caught by both experimental gillnets were greater than the maturity size (752 mm total length). A logit cubic curve showed the best fit for the comparison, having the lowest Akaike Information Criterion (AIC) value and with all model parameters being statistically significant (Table 2). The GLMM model showed that the control gillnets caught more fish at total lengths smaller than 960 mm, while the experimental gillnets caught more individuals at total lengths larger than 1150 mm (Figure 6B). The significant differences in catch-at-length between the control vs. experimental gillnets were shown where the confidence intervals (CIs) did not overlap the 0.5 band. Contrastingly, there was no difference in size-based selectivity between the control and experimental nets for the moderate-sized fish (i.e., 450–600 mm and 960–1150 mm) based on the CI area overlap at the 0.5 band (Figure 6B).

4. Discussion

Modifying fishing gear is one of the few ways to assess the utility of a key technical modification on the gillnet catches of a migratory species, in order to increase captures or improve gear selectivity. In this study, we showed that the experimental gillnet with multiple mesh sizes catches narrow-barred Spanish mackerel in comparable amounts to the control net, while it selects a range of sizes extended toward larger individuals, which is reflected in the caught biomass, ultimately increasing the revenues of the narrow-barred Spanish mackerel gillnet fisheries. Like other passive gears (set-net [13], pot [50], trammel net [51], and fyke net [52]), the catch of gillnet depends on temporal (i.e., seasonal migration and natural diel movement) and spatial (i.e., depth and locations) factors. The present study shows that mixed gillnets had higher catch rates in autumn under dark conditions. Finally, this study adds further evidence to the fact that fishermen can obtain their catch with improved size selectivity through suitable modifications of fishing gear, and mixed gillnets represent an alternative to the traditional gillnets in mitigating the capture of small sizes of fish species targeted by gillnet fisheries.
As expected, our results show that larger narrow-barred Spanish mackerel were captured by the mixed gillnets across the entire targeted length range compared to the traditional gillnets. In other words, the mean lengths of fish increased with increasing mesh size, and this is typical for the gillnet selectivity feature [53]. A consistent feature of the gillnet fisheries is represented by the selectivity of the captured fish size along with the net mesh size [15,22,54]. Our experiment indicates that the catch of the experimental gillnets, which had larger mesh sizes in the bottom, captured larger fish compared to the single-mesh-size gillnets. This outcome is possibly related to the vertical diel migration of narrow-barred Spanish mackerel, where larger individuals aggregate near the seabed and forage food in demersal habitats, while small and young fish live in the upper water column [14,16,55]. Diel vertical migration and distribution apparently depend on the oceanographic conditions, in particular, the seasonal stratification of the water column, because diel effects on catch rates are more pronounced during the autumn when the water column is thermally stratified than during spring and winter when the water column is well mixed [56]. Seasonality also influences the catch efficiency of narrow-barred Spanish mackerel gillnets [15]. For example, [15] show that gillnets catch larger percentages of adults during autumn and winter, and catch rates significantly decrease in the spring. Our results show that the catch of mixed gillnets peaks in September.
Gillnetting is different from most other fishing methods, which commonly reduce the catch rates once increasing mesh sizes, which is not acceptable from the fishermen’s perspective. The mixed gillnets used in our experiments captured the same amounts of fish as the traditional gillnets, but the substantially extended the size of the captured individuals in the upper limit of the range. This is an important contribution because fishermen can improve the weight per unit effort and sell fish at higher prices. Our mixed gillnets have an efficient catch; perhaps we chose an effective hanging ratio and materials, which made fish catching easily [15].
As other pelagic species, the catch of mackerel species in this study was influenced by the lunar phases. Moonlight reflection on the net while fishing in shallow water might potentially change the behavioral responses of the target and bycatch species to the fishing gear, resulting in a lower catch rate under high moonlight intensity. This is sustained by previous observations of other species and fisheries [19,41,57]. For example, the catch rates of pole-and-line fisheries catching yellowfin tuna (Thunnus albacares) during the full-moon period are one third of those in the new-moon phase [41]. Purse seine and stick-held falling nets with artificial light are often suspended during the high moonlight intensity period (i.e., 10th–20th of lunar month) [18,19]. The target species of the gillnet fisheries in this study, the narrow-barred Spanish mackerel, spotted mackerel, and wahoo, were more responsive to the nocturnal light condition. These species reportedly exhibit shallower nighttime distributions around new moons and deeper distributions when the lunar illumination is high, presumably in association with the vertical distribution of prey [55].
We measured higher catch rates of narrow-barred Spanish mackerel and wahoo in the south of Vietnam compared to the Gulf of Tonkin study site using both gear types. Other studies also showed pronounced differences in catches among fishing sites [22,23], which is not surprising for gillnet fisheries that depend on fish occurrence, density, mobility, diel movements, and seasonal migration [1]. Higher catch rates in the south of Vietnam are consistent with natural resource distribution in this area [58,59]. Additionally, Vietnamese coastal areas are known to exhibit different habitats and environmental conditions, which could also influence fishing efficiency [60].
Mixed gillnets captured the same fish species that traditional gillnets did, and both gear types captured few spottail sharks (Carcharhinus sorrah) and bronze croakers (Otolithoides biauritus), which are protected species in Vietnam [61]. Further research on gear modification and fish behavior is needed in order to avoid incidental catches of protected or otherwise undesired species. A reduction in effort in terms of either soak time or type of gears used, or both, could lead to a reduction in the catches of undesired species. Unlike for regional pole-and-line fisheries, no marine turtles were caught in the present study [41].
While the traditional gillnet with single-small-mesh sizes has become part of the social license to catch multiple species in the waters of Vietnam, some enhancements can be introduced. Fishing with mixed gillnets requires minimal vessel or equipment modifications to use the new gear. Importantly, the investment cost of the new gear is similar to that already adopted by fishermen. Although there have been several studies on the gillnet modification targeting pelagic species in Vietnam [22,23], our results show the first successful application of mixed gillnets to improve the catch efficiency by catching larger fish sizes. As a result of the findings from our study, the commercial fisheries has generally shifted to the mixed gillnet technique throughout coastal communities in Vietnam, reporting results very similar to our research findings. Mixed gillnet fisheries deserves attention in the future because of the herein reported benefits. Monitoring this modified gear to collect data on stock selectivity, measuring bycatch, and resource management is recommended.

5. Conclusions

Marine fisheries have a very important role in the socioeconomic development throughout coastal communities, because many millions of Vietnamese directly and/or indirectly rely on capturing marine fish. Although traditional gillnets show good performance of catching, modifications are available and needed. Our results show that experimental gillnets tested in this study provide a promising alternative to the single-mesh-size gillnets. The benefit of mixed gillnets for the fishermen is to increase the weight per unit effort of the target species, and given the broad application of this gear type, the fishermen are required to make a minimal adjustment and upgrade their current nets and vessels. The new type of gear does not add extra operational costs compared to the traditional gillnets. In addition to the potential economic benefits, widespread use of mixed gillnets contributes to the maintenance of the narrow-barred Spanish mackerel stock, resulting in large fish sizes being caught.

Author Contributions

Conceptualization, L.T.N. and K.Q.N.; methodology, L.T.N. and K.Q.N.; software, L.T.N. and K.Q.N.; validation, L.T.N. and K.Q.N.; formal analysis, L.T.N. and K.Q.N.; investigation, L.T.N. and K.Q.N.; resources, T.P.N.; data curation, L.T.N. and K.Q.N.; writing—original draft preparation, L.T.N. and K.Q.N.; writing—review and editing, L.T.N., K.Q.N. and T.P.N.; visualization, L.T.N. and K.Q.N.; project administration, T.P.N.; funding acquisition, T.P.N. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

This study did not target and involve endangered or protected species. Sea trials were conducted on board a commercial fishing vessel, which required no experimental permit. The animals were naturally kills as same as the normal fishing practices.

Data Availability Statement

The data that support the results of this study are available from the corresponding author upon reasonable request.

Acknowledgments

We are grateful to captains Nguyễn Văn Kỷ, Võ Ngọc Anh, and Nguyễn Văn Thế and their crew for the valuable assistance on board the vessel. The Institute of Marine Science and Fishing Technology of Nha Trang University and Research Institute for Marine Fisheries provided resources and assistance to conduct this study. We extend great thanks to Trần Đức Phú for consulting on the statistical analyses and providing valuable comments on an earlier version of the manuscript. The study could not have been performed without their kind help and support. Finally, we are grateful to the editor and two anonymous reviewers for helpful reviews on early drafts.

Conflicts of Interest

The author declares no conflict of interest.

References

  1. Rudstam, L.G.; Magnuson, J.J.; Tonn, W.M. Size selectivity of passive fishing gear: A correction for encounter probability applied to gillnets. Can. J. Fish. Aquat. Sci. 1984, 41, 1252–1255. [Google Scholar] [CrossRef]
  2. Brandt, V. Fishing Catching Methods of the World. In Fish Catching Methods of the World, 4th ed.; Gabriel, O., Lange, K., Dahm, E., Wendt, T., Eds.; Blackwell Publishing Ltd.: Oxford, UK, 2005; 523p. [Google Scholar]
  3. FAO. Abandoned, Lost and Discarded Gillnets and Trammel Nets: Methods to Estimate Ghost Fishing Mortality, and the Status of Regional Monitoring and Management; FAO Fisheries and Aquaculture Technical Paper No. 600; FAO: Rome, Italy, 2006; 79p, ISBM 978-92-5-108917-0. [Google Scholar]
  4. Standal, D.; Grimaldo, E.; Larsen, R.B. Governance implications for the implementation of biodegradable gillnets in Norway. Mar. Policy 2020, 122, 104238. [Google Scholar] [CrossRef]
  5. Meintzer, P.; Walsh, P.; Favaro, B. Comparing catch efficiency of five models of pot for use in a Newfoundland and Labrador cod fishery. PLoS ONE 2018, 13, e0199702. [Google Scholar] [CrossRef] [PubMed]
  6. Ehrhardt, N.M.; Die, D.J. Selectivity of Gill Nets Used in the Commercial Spanish Mackerel Fishery of Florida. Trans. Am. Fish. Soc. 1998, 117, 574–580. [Google Scholar] [CrossRef]
  7. Hamley, J. Review of gillnet selectivity. J. Fish. Res. Board Can. 1975, 32, 1943–1969. [Google Scholar] [CrossRef]
  8. Benjamins, S.; Ledwell, W.; Huntington, J.; Davidson, A.R. Assessing changes in numbers and distribution of large whale entanglements in Newfoundland and Labrador, Canada. Mar. Mammal Sci. 2012, 28, 579–601. [Google Scholar] [CrossRef]
  9. Shester, G.G.; Micheli, F. Conservation challenges for small-scale fisheries: Bycatch and habitat impacts of traps and gillnets. Biol. Conserv. 2011, 144, 1673–1681. [Google Scholar] [CrossRef]
  10. Ortiz, N.; Mangel, J.C.; Wang, J.; Alfaro-Shigueto, J.; Pingo, S.; Jimenez, A.; Suarez, T.; Swimmer, Y.; Carvalho, F.; Godley, B.J. Reducing green turtle bycatch in small-scale fisheries using illuminated gillnets: The cost of saving a sea turtle. Mar. Ecol. Prog. Ser. 2016, 545, 251–259. [Google Scholar] [CrossRef]
  11. Bayse, S.M.; Grant, S.M. Effect of baiting gillnets in the Canadian Greenland halibut fishery. Fish. Manag. Ecol. 2020, 27, 523–530. [Google Scholar] [CrossRef]
  12. Matsuoka, T.; Nakashima, T.; Nagasawa, N. A review of ghost fishing: Scientific approaches to evaluation and solutions. Fish. Sci. 2005, 71, 691–702. [Google Scholar] [CrossRef]
  13. Nguyen, K.Q.; Nguyena, V.Y. Changing of sea surface temperature affects catch of Spanish mackerel Scomberomorus commerson in the set-net fishery. Fish. Aquac. J. 2017, 8, 231. [Google Scholar] [CrossRef]
  14. Niamaimandi, N.; Kaymaram, F.; Hoolihan, J.P.; Mohammadi, G.H.; Fatemi, S.M.R. Population dynamics parameters of narrow-barred Spanish mackerel, Scomberomorus commerson (Lacèpéde, 1800), from commercial catch in the northern Persian Gulf. Glob. Ecol. Conserv. 2015, 4, 666–672. [Google Scholar] [CrossRef]
  15. Pouladi, M.; Paighambari, S.Y.; Broadhurst, M.K.; Millar, R.B.; Eighani, M. Effects of season and mesh size on the selection of narrow-barred Spanish mackerel, Scomberomorus commerson in the Persian Gulf artisanal gillnet fishery. J. Mar. Biol. Assoc. United Kingd. 2020, 100, 1321–1325. [Google Scholar] [CrossRef]
  16. Grandcourt, E.M.; Al Abdessalaam, T.Z.; Francis, F.; Al Shamsi, A.T. Preliminary assessment of the biology and fishery for the narrow-barred Spanish mackerel, Scomberomorus commerson (Lacépède, 1800), in the southern Arabian Gulf. Fish. Res. 2005, 76, 277–290. [Google Scholar] [CrossRef]
  17. FAO. Scomberomorus commerson Lacepède, 1800. Fisheries and Aquaculture Division. Rome. 2023. Available online: https://www.fao.org/fishery/en/aqspecies/3280/en (accessed on 18 February 2023).
  18. Nguyen, K.Q.; Tran, P.D.; Nguyen, L.T.; To, P.V.; Morris, C.J. Use of light-emitting diode (LED) lamps in combination with metal halide (MH) lamps reduce fuel consumption in the Vietnamese purse seine fishery. Aquac. Fish. 2021, 6, 432–440. [Google Scholar] [CrossRef]
  19. Nguyen, L.T.; Nguyen, T.P.; Do, T.V.; Nguyen, K.Q. Light-emitting diode (LED) lights reduce the fuel consumption and maintain the catch rate of stick-held falling net fisheries. Reg. Stud. Mar. Sci. 2022, 55, 102542. [Google Scholar] [CrossRef]
  20. Pham, T.D.T.; Huang, H.W.; Chuang, C.T. Finding a balance between economic performance and capacity efficiency for sustainable fisheries: Case of the Da Nang gillnet fishery, Vietnam. Mar. Policy. 2014, 44, 287–294. [Google Scholar] [CrossRef]
  21. Duy, N.N.; Flaaten, O.; Anh, N.T.K.; Ngoc, Q.T.K. Open-access fishing rent and efficiency-The case of gillnet vessels in Nha Trang, Vietnam. Fish. Res. 2012, 127–128, 98–108. [Google Scholar] [CrossRef]
  22. Tuyen, P.V.; Toan, N.P. Trial results of improvement combinated gillnet in the Tokin Gulf. Can Tho Univ. J. Sci. 2016, 45, 128–135. [Google Scholar]
  23. Long, N.T. Study on the status of mixed gillnet fisheries in Tra Vinh province. Can Tho Univ. J. Sci. 2017, 49, 109–115. [Google Scholar] [CrossRef]
  24. Nguyen, L.T. Study on the mesh size selectivity of inshore gillnet fishery in the sea areas of Quang Dien district. J. Fish. Sci. Technol. 2022, 1, 2–11, (In Vietnamese with English Abstract). [Google Scholar]
  25. Vu, N.P.U.; Đinh, H.B.; Thao, L.T.T.; Hoa, T.T.H.; Quang, V.V. Common fishes composition of some demersal fishing gears at coastal waters of Khanh Hoa province. In Proceedings of the National Conference Bien Dong—2007, Nha Trang, Vietnam, 12–14 September 2007. [Google Scholar]
  26. Tint, K.K.; Ngin, K.; Sapari, A.; Souliphone, K.; Suwannapoom, S.; Viron, J.G.; Thanh, V.T.P. Enhancing the management of the Indo-Pacific mackerel resources in the Gulf of Thailand: A synthesis. Fish People 2020, 18, 14–19. [Google Scholar]
  27. Heikinheimo, O.; Setälä, J.; Saarni, K.; Raitaniemi, J. Impacts of mesh-size regulation of gillnets on the pikeperch fisheries in the Archipelago Sea, Finland. Fish. Res. 2006, 77, 192–199. [Google Scholar] [CrossRef]
  28. Šmejkal, M.; Ricard, D.; Prchalová, M.; Říha, M.; Muška, M.; Blabolil, P.; Čech, M.; Vašek, M.; Jůza, T.; Herreras, A.M.; et al. Biomass and abundance biases in European standard gillnet sampling. PLoS ONE 2015, 10, e0128469. [Google Scholar] [CrossRef] [PubMed]
  29. Rotherham, D.; Gray, C.A.; Broadhurst, M.K.; Johnson, D.D.; Barnes, L.M.; Jones, M.V. Sampling estuarine fish using multi-mesh gill nets: Effects of panel length and soak and setting times. J. Exp. Mar. Bio. Ecol. 2006, 331, 226–239. [Google Scholar] [CrossRef]
  30. Hien, H.V.; Phuong, D.T.; Quyen, N.T.K.; Hung, C.V.; Trieu, N.P. Efficiency of fishing activities of trawlers and gillnets on the coast of Ben Tre province. Hue Univ. J. Sci. Agric. Rural Dev. 2022, 131, 163–174. [Google Scholar]
  31. Van, V.T.T.; Hung, C.V.; Anh, N.L. The diversity of species composition identified in the main fishing occupations (trawling, gill netting, trapping) in the sea of Ben Tre province. J. Fish. Sci. Technol. 2022, 1, 80–89, (In Vietnames with English Abstract). [Google Scholar]
  32. He, P.; Pol, M. Fish behavior near gillnets: Capture processes, and influencing factors. In Behavior of Marine Fishes: Capture Processes and Conservation Challenges; He, P., Ed.; Willey-Blackwel: Hoboken, NJ, USA, 2010; pp. 183–203. [Google Scholar]
  33. He, P. Gillnets: Gear design, fishing performance and conservation challenges. Mar. Tecnol. Soc. J. 2006, 40, 12–19. [Google Scholar] [CrossRef]
  34. Duman, E.; Pala, M. Effect of water temperature on the selectivity of monofilament gill nets (PA). Pak. J. Biol. Sci. 2007, 10, 1914–1917. [Google Scholar] [CrossRef]
  35. Bacalso, R.T.M.; Romagnoni, G.; Mesa, S.; Wolff, M. Annual and seasonal environmental drivers of species- and gear-specific catch rates in the Visayan Sea, Philippines. Reg. Stud. Mar. Sci. 2023, 57, 102734. [Google Scholar] [CrossRef]
  36. Gray, C.A.; Broadhurst, M.K.; Johnson, D.D.; Young, D.J. Influences of hanging ratio, fishing height, twine diameter and material of bottom-set gillnets on catches of dusky flathead Platycephalus fuscus and non-target species in New South Wales, Australia. Fish. Sci. 2005, 71, 1217–1228. [Google Scholar] [CrossRef]
  37. Grimaldo, E.; Herrmann, B.; Su, B.; Føre, H.M.; Vollstad, J.; Olsen, L.; Larsen, R.B.; Tatone, I. Comparison of fishing efficiency between biodegradable gillnets and conventional nylon gillnets. Fish. Res. 2019, 213, 67–74. [Google Scholar] [CrossRef]
  38. Cerbule, K.; Herrmann, B.; Grimaldo, E.; Larsen, R.B.; Savina, E.; Vollstad, J. Comparison of the efficiency and modes of capture of biodegradable versus nylon gillnets in the Northeast Atlantic cod (Gadus morhua) fishery. Mar. Pollut. Bull. 2022, 178, 113618. [Google Scholar] [CrossRef]
  39. R Development Core-Team. R: A Language and Environment for Statistical Computing; R Foundation for Statistical Computing: Vienna, Austria, 2021; Available online: http://www.R-project.org (accessed on 10 February 2023).
  40. Beck, N.; Jackman, S. Beyond linearity by default: Generalized additive models. Am. J. Pol. Sci. 1998, 42, 596–627. [Google Scholar] [CrossRef]
  41. Nguyen, K.Q.; Nguyen, B.V.; Phan, H.T.; Nguyen, L.T.; To, P.V.; Tran, H.V. A comparison of catch efficiency and bycatch reduction of tuna pole-and-line fisheries using Japan tuna hook (JT-hook) and circle-shaped hook (C.-hook). Mar. Freshw. Res. 2022, 73, 662–677. [Google Scholar] [CrossRef]
  42. Lehmann, A.; Overton, J.M.; Leathwick, J.R. GRASP: Generalized regression analysis and spatial prediction. Ecol. Modell. 2002, 157, 189–207. [Google Scholar] [CrossRef]
  43. Sandman, A.; Isaeus, M.; Bergström, U.; Kautsky, H. Spatial predictions of Baltic phytobenthic communities: Measuring robustness of generalized additive models based on transect data. J. Mar. Syst. 2008, 74, 86–96. [Google Scholar] [CrossRef]
  44. Björnstad, O.N.; Falck, W. Nonparametric spatial covariance functions: Estimation and testing. Environ. Ecol. Stat. 2001, 8, 53–70. [Google Scholar] [CrossRef]
  45. Holst, R.; Revill, A. A simple statistical method for catch comparison studies. Fish. Res. 2009, 95, 254–259. [Google Scholar] [CrossRef]
  46. Tran, P.D.; Nguyen, L.T.; To, P.V.; Nguyen, K.Q. Effects of the trap entrance designs on the catch efficiency of swimming crab Charybdis feriata fishery. Fish. Res. 2020, 232, 105730. [Google Scholar] [CrossRef]
  47. Nguyen, L.T.; Nguyen, K.Q. Effects of jig location and soak time on catch rates of a novel fishing gear design of squid longline fisheries. Reg. Stud. Mar. Sci. 2022, 52, 102312. [Google Scholar] [CrossRef]
  48. Bates, D.M.; Maechler, M.; Bolker, B.; Walker, S. Fitting linear mixed-effects models using lme4. J. Stat. Softw. 2015, 67, 1–48. [Google Scholar] [CrossRef]
  49. Bolker, B. Package ‘Bbmle’. Tools for General Maximum Likelihood Estimation. 2020. Available online: https://cran.r-project.org/web/packages/bbmle/index.html (accessed on 12 February 2023).
  50. Nguyen, K.Q.; Morris, C.J. Fishing for Atlantic cod (Gadus morhua) with pots and gillnets: A catch comparison study along the southeast coast of Labrador. Aquac. Fish. 2022, 7, 433–440. [Google Scholar] [CrossRef]
  51. Ganias, K.; Christidis, G.; Kompogianni, I.F.; Simeonidou, X.; Voultsiadou, E.; Antoniadou, C. Fishing for cuttlefish with traps and trammel nets: A comparative study in Thermaikos Gulf, Aegean Sea. Fish. Res. 2020, 234, 105783. [Google Scholar] [CrossRef]
  52. Oksanen, S.M.; Ahola, M.P.; Oikarinen, J.; Kunnasranta, M. A novel tool to mitigate by-catch mortality of Baltic Seals in coastal fyke net fishery. PLoS ONE 2015, 10, e0127510. [Google Scholar] [CrossRef]
  53. Holst, R.; Madsen, N.; Fonseca, P.; Moth-Poulsen, T.; Campos, A. Manual for Gillnet Selectivity; European Commission: Luxembourg, 1998; 43p. [Google Scholar]
  54. Paukert, C.P.; Fisher, W.L. Evaluation of Paddlefish length distributions and catch rates in three mesh sizes of gill nets. N. Am. J. Fish. Manag. 1999, 19, 599–603. [Google Scholar] [CrossRef]
  55. Kim, H.; Lim, Y.N.; Song, S.H.; Kim, Y.H. Understanding the migration path of Spanish Mackerel Scomberomorus niphonius using catch distributions. Korean J. Fish. Aquat. Sci. 2016, 49, 376–384. [Google Scholar]
  56. Mathew, M.; Makhankova, A.; Menier, D.; Sautter, B.; Betzler, C.; Pierson, B. The emergence of Miocene reefs in South China Sea and its resilient adaptability under varying eustatic, climatic and oceanographic conditions. Sci. Rep. 2020, 10, 7141. [Google Scholar] [CrossRef]
  57. Afonso, A.S.; Mourato, B.; Hazin, H.; Hazin, F.H.V. The effect of light attractor color in pelagic longline fisheries. Fish. Res. 2021, 235, 2021. [Google Scholar] [CrossRef]
  58. Vinh, C.T. Assessment of relative abundance of fishes caught by gillnet in Vietnamese waters. In Proceedings of the Fourth Technical Seminar on Marine Fishery Resources Survey in the South China Sea, Area IV: Vietnamese Waters, Bangkok, Thailand, 18–20 September 2000; pp. 10–28. [Google Scholar]
  59. Tran, D.D.; Cao, H.V.; Dinh, Q.M.; Tran, L.X. An assessment of fisheries resources in the coastal water of the Mekong Delta, Vietnam. AACL Bioflux. 2020, 13, 3683–3694. [Google Scholar]
  60. Jaureguizar, A.J.; Cortés, F.; Milessi, A.C.; Cozzolino, E.; Allega, L. A trans-ecosystem fishery: Environmental effects on the small-scale gillnet fishery along the Río de la Plata boundary. Estuar. Coast. Shelf Sci. 2015, 166, 92–104. [Google Scholar] [CrossRef]
  61. Phung, T.D. Circular No. 13/2020/TT-BNNPTNT Dated November 9, 2020 on Amendments to Circular No. 21/2018/TT-BNNPTNT on Record and Submission of Reports and Diaries on Fishery Activities; Announcement of Appointed Ports for Verifying Origin of Extracted Fisheries. 2020. Available online: https://www.mard.gov.vn/Pages/vbpq-toanvan.aspx?ItemID=144999 (accessed on 20 January 2023).
Fishes 08 00210 g001 550
Figure 1. Map of Vietnam (A) including Gulf of Tonkin (red rectangular), center (blue rectangular), and south (green rectangular) study sites, and insets zoomed in on right (B–D) represent those study sites, respectively. Each blue x and red dot in the right panels indicates the location of a set of control gillnets and experimental gillnets, respectively, that were deployed during the study.
Figure 1. Map of Vietnam (A) including Gulf of Tonkin (red rectangular), center (blue rectangular), and south (green rectangular) study sites, and insets zoomed in on right (B–D) represent those study sites, respectively. Each blue x and red dot in the right panels indicates the location of a set of control gillnets and experimental gillnets, respectively, that were deployed during the study.
Fishes 08 00210 g001
Fishes 08 00210 g002 550
Figure 2. Schematic representation of the experimental (top panel) and control (bottom panel) gillnets tested during the fishing trials. Pb—Plumbum is lead; PP and PE are polypropylene and polyethylene, respectively; Ø is diameter; D is denier; and E is hanging ratio.
Figure 2. Schematic representation of the experimental (top panel) and control (bottom panel) gillnets tested during the fishing trials. Pb—Plumbum is lead; PP and PE are polypropylene and polyethylene, respectively; Ø is diameter; D is denier; and E is hanging ratio.
Fishes 08 00210 g002
Fishes 08 00210 g003 550
Figure 3. Mean CPUE (number of fish caught per h for webbing) of narrow-barred Spanish mackerel, spotted mackerel, and wahoo caught by control (red) and experimental (blue) gillnets. Points represent mean catch. Bars are 95% confidence intervals. Negative confidence intervals indicate that they are not statistically significant.
Figure 3. Mean CPUE (number of fish caught per h for webbing) of narrow-barred Spanish mackerel, spotted mackerel, and wahoo caught by control (red) and experimental (blue) gillnets. Points represent mean catch. Bars are 95% confidence intervals. Negative confidence intervals indicate that they are not statistically significant.
Fishes 08 00210 g003
Fishes 08 00210 g004 550
Figure 4. Mean CPUE (number of fish caught per h for webbing) of narrow-barred Spanish mackerel, spotted mackerel, and wahoo caught in the Gulf of Tonkin (green), center (red), and south (blue) of Vietnam. Points represent mean catch. Bars are 95% confidence intervals. Negative confidence intervals indicate that they are not statistically significant.
Figure 4. Mean CPUE (number of fish caught per h for webbing) of narrow-barred Spanish mackerel, spotted mackerel, and wahoo caught in the Gulf of Tonkin (green), center (red), and south (blue) of Vietnam. Points represent mean catch. Bars are 95% confidence intervals. Negative confidence intervals indicate that they are not statistically significant.
Fishes 08 00210 g004
Fishes 08 00210 g005 550
Figure 5. Predicted CPUE (number of fish caught per h for webbing) obtained from the GAMs for catch of narrow-barred Spanish mackerel, spotted mackerel, and wahoo in relation to moon phase (A–C), fishing month (D–F), and depth (G–I). Blue curves indicate mean values obtained from the models. Shaded areas represent 95% confidence intervals. Negative confidence intervals indicate that they are not statistically significant.
Figure 5. Predicted CPUE (number of fish caught per h for webbing) obtained from the GAMs for catch of narrow-barred Spanish mackerel, spotted mackerel, and wahoo in relation to moon phase (A–C), fishing month (D–F), and depth (G–I). Blue curves indicate mean values obtained from the models. Shaded areas represent 95% confidence intervals. Negative confidence intervals indicate that they are not statistically significant.
Fishes 08 00210 g005
Fishes 08 00210 g006 550
Figure 6. Length frequency curves for narrow-barred Spanish mackerel captured by the control and experimental gillnets (A). GLMM results for the proportion of the total catch retained by control gillnets compared with experimental gillnets (B). The vertical blue dashed line in the top panel indicates the maturity size of narrow-barred Spanish mackerel at 752 mm total length. The horizontal dashed line at 0.5 in the bottom panel indicates equal performance of both experimental gears. A value of 0.25 indicates the given length class where 25% of fish were captured by the experimental gillnets and 75% of fish were captured by control gillnets. Contrastingly, a value of 0.75 means that 75% of fish were caught by the experimental and 25% by the control gillnets. The solid black curve in the bottom panel models the mean total length at given size, while the gray shaded areas are the 95% confidence intervals. If confidence intervals overlap at 0.5, then there is no statistically significant difference in catch-at-length between control and experimental gillnets at the given length class.
Figure 6. Length frequency curves for narrow-barred Spanish mackerel captured by the control and experimental gillnets (A). GLMM results for the proportion of the total catch retained by control gillnets compared with experimental gillnets (B). The vertical blue dashed line in the top panel indicates the maturity size of narrow-barred Spanish mackerel at 752 mm total length. The horizontal dashed line at 0.5 in the bottom panel indicates equal performance of both experimental gears. A value of 0.25 indicates the given length class where 25% of fish were captured by the experimental gillnets and 75% of fish were captured by control gillnets. Contrastingly, a value of 0.75 means that 75% of fish were caught by the experimental and 25% by the control gillnets. The solid black curve in the bottom panel models the mean total length at given size, while the gray shaded areas are the 95% confidence intervals. If confidence intervals overlap at 0.5, then there is no statistically significant difference in catch-at-length between control and experimental gillnets at the given length class.
Fishes 08 00210 g006
Table
Table 1. Summary of all species captured during the fishing experiment for control and experimental gillnets.
Table 1. Summary of all species captured during the fishing experiment for control and experimental gillnets.
SpeciesScientific NameSpecies Captured by Net Type in Number
ControlExperimental
Target species (retained)
Narrow-barred Spanish mackerelScomberomorus commerson32,00029,900
Spotted mackerelScomberomorus guttatus900700
WahooAcanthocybium solandri96007600
Byproduct (retained)
TripletailLobotes surinamensis299199
BarramundiLates calcarifer98100
PilotfishNaucrates ductor2990
Black pomfretFormio niger500498
Bronze croakerOtolithoides biauritus2010
Bullet tunaAuxis rochei15011599
CobiaRachycentron canadum0100
Daggertooth pike congerMuraenesox cinereus98199
Dogtooth tunaGymnosarda unicolor299199
Frigate tunaAuxis thazard thazard903598
Giant catfishArius thalassinus1501100
Great barracudaSphyraena barracuda299299
Largehead hairtailTrichiurus lepturus98100
Yellow-spotted skateRaja hollandi98199
Indian threadfinPolynemus indicus3301399
Japanese scadDecapterus maruadsi0299
Longtail tunaThunnus tonggol201100
Common dolphinfishCoryphaena hippurus299100
Red bigeyePlectorhynchus hamrur98199
Crimson snapperLutjanus erythropterus0100
Shortfin scadDecapterus macrosoma2010
Silver pomfretPampus argenteus98100
Elongate ilishaIlisha elongata98100
Spottail sharkCarcharhinus sorrah1898598
Small spotted dartTrachinotus bailloni903199
SwordfishXiphias gladius1501399
Talang queenfishScomberoides commersonianus2010
White-spotted grouperEpinephelus caeruleopunctatus0199
Yellowfin tunaThunnus albacares0100
Table
Table 2. GLMM results for the control vs. experimental gillnet comparison. Bold p-values denote the selected model with the lowest AIC and the model parameters resulted in being statistically significant. SE is the standard error of the estimate.
Table 2. GLMM results for the control vs. experimental gillnet comparison. Bold p-values denote the selected model with the lowest AIC and the model parameters resulted in being statistically significant. SE is the standard error of the estimate.
ModelAICParameterEstimateSEz-Valuep
Constant5246.4β0−0.070.01−8.44<0.001
Linear3588.3β0−5.040.06−105.70<0.001
β10.010.05106.600.53
Quadratic2615.5β09.090.30195.00<0.001
β1−0.030.01−572.200.469
β20.700.02277.80<0.001
Cubic2389.5β0−14.400.05−306.18<0.001
β10.070.011279.74<0.001
β23.000.40−1473.23<0.001
β35.700.700.72<0.001
Quartic5663.3β0−21.590.33−65.64<0.001
β10.110.01294.14<0.001
β2−2.400.67−377.95<0.001
β35.301.400.250.42
β4<0.01<0.010.020.59
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Nguyen, L.T.; Nguyen, K.Q.; Nguyen, T.P. Experimental Mixed Gillnets Improve Catches of Narrow-Barred Spanish Mackerel (Scomberomorus commerson). Fishes 2023, 8, 210. https://doi.org/10.3390/fishes8040210

AMA Style

Nguyen LT, Nguyen KQ, Nguyen TP. Experimental Mixed Gillnets Improve Catches of Narrow-Barred Spanish Mackerel (Scomberomorus commerson). Fishes. 2023; 8(4):210. https://doi.org/10.3390/fishes8040210

Chicago/Turabian Style

Nguyen, Luong Trong, Khanh Quoc Nguyen, and Toan Phi Nguyen. 2023. "Experimental Mixed Gillnets Improve Catches of Narrow-Barred Spanish Mackerel (Scomberomorus commerson)" Fishes 8, no. 4: 210. https://doi.org/10.3390/fishes8040210

Article Metrics

Back to TopTop