Impact of Regional Wind Changes on Trawl Fishing Effort Under the Pressure of Overfishing in the Iskenderun Bay

Abstract

This study was conducted to examine the effects of regional wind changes on trawl fishing effort in Iskenderun Bay from 2017 to 2023 by analyzing meteorological data, daily fishing durations, and catch quantities. It was found that an increase in wind intensity reduced fishing durations by an average of 0.367 h. Northerly and easterly winds were observed to have higher speeds throughout the year, with the highest speeds reaching 14 m/s in March. Fishing activities were affected more by southerly and westerly winds due to the geographical structure of Iskenderun Bay. Seasonal variations were also detected, with fishing durations being longer at the beginning of the fishing season in autumn and decreasing in spring. Species such as red mullet, brushtooth lizardfish, and shrimp were identified as having a significant impact on fishing activities. The relationships between wind intensity, direction, and fishing durations were revealed through statistical analyses. It was shown that environmental and seasonal factors influenced trawl fishing effort in Iskenderun Bay. These results provided insights into the interactions between wind dynamics and fishing operations.

1. Introduction

The fish stocks in the Mediterranean are at risk of losing their sustainability due to high fishing pressure [1,2,3]. According to research by Froese et al. [4], only 20% of the 181 assessed stocks in the Mediterranean and Black Sea are caught at the Maximum Sustainable Yield (MSY) level, while 60% are critically depleted. In 2012, the proportion of overfished stocks was 88%, which decreased to 75% in 2018 [5]. However, despite this decline, overfishing remains a significant issue.

Iskenderun Bay is one of the regions in the Mediterranean where fishing pressure is felt most intensely [6,7,8,9,10]. Approximately 45 trawl fishing vessels operate actively in the bay, and the 2270 km² bay area can be entirely covered by these vessels within just 15 days [11]. Despite increasing fishing effort, the productivity of fisheries in the region has declined over the years [12]. Species in the Eastern Mediterranean have developed different strategies to cope with fishing pressure. For instance, local species such as Mullus barbatus and Pagellus erythrinus attempt to adapt by growing rapidly, reaching sexual maturity early, and having short reproductive cycles. However, their populations continue to decline due to overfishing. The intense fishing pressure on demersal species has led to structural changes in their populations, causing young individuals to be captured at an earlier stage, which disrupts their reproductive cycles and hinders stock recovery. Nevertheless, seasonal fishing bans during the summer months allow juvenile individuals to concentrate in coastal waters, improving the survival chances of some species [13].

Climate change has negatively impacted marine fisheries, placing pressure on national economies, particularly through the increase in ocean temperatures and acidification of the seas. These changes lead to a decline in fish stocks and the migration of marine species, necessitating modifications in fishing areas and schedules [14]. Weather-related downtime is a significant factor affecting fishing activities and income. In particular, fishermen on the East Coast of Peninsular Malaysia are more affected compared to those on the West Coast [15]. Cheung et al. [16] highlight that fishermen’s perception of climate change varies significantly depending on geographic and cultural contexts. For example, in Senegal, nearly all fishermen acknowledge the effects of climate change and rely on weather forecasts to determine when to go out to sea. This demonstrates their awareness of the importance of climatic conditions for safe and efficient fishing operations [17]. Nagy et al. [18] directly examine the effects of climate change on the circulation patterns in the upper layers of the Eastern Mediterranean using the Med-ROMS model.

It has been reported that sea surface temperatures in the Mediterranean have increased by approximately 1.0 °C since 1993, while the mean sea level has been rising at a rate of 2.5 mm per year [19]. Recent studies predict a potential warming of up to 5 °C in the region by the end of the century, with sea temperatures expected to rise between 1.8 °C and 3.5 °C by 2100 [20]. Climate change has led to significant alterations in wind patterns in the Eastern Mediterranean. Seasonal variations indicate a decrease in wind speed in the northern regions during winter, while an increase is expected in the southern areas. In summer, changes in specific wind systems, such as the Etesian winds, are projected. These shifts can directly impact ocean currents, weather patterns, and maritime activities in the region [21].

Changes in wind patterns and increasing wind speeds can directly affect maritime activities. Stronger winds make sea conditions more dangerous, limiting the time fishing vessels can safely remain at sea. Additionally, altered wind patterns influence surface currents and nutrient distribution, affecting plankton populations and, consequently, fish stocks [21]. These changes make fishing more costly and risky, particularly for small-scale fishermen, threatening their livelihoods and local food security.

Focusing on Iskenderun Bay, the local impacts of climate change are evident through previous studies and the observations of local fishermen [22,23,24,25]. Research has been conducted to determine how changes in wind patterns influence the duration of intensive trawl fishing operations.

2. Materials and Methods

In this study, conducted in Iskenderun Bay under the pressure of excessive fishing, (1) meteorological data and (2) daily working hours of fishing vessels at sea for the years 2017 and 2023 have been obtained daily. (3) The quantities of fish caught by these trawl fishing vessels have been obtained from commercial trawl fishing records, with daily estimates calculated based on the duration of each fishing trip (usually 1 night and 2 days) for the last three years (2021–2023). The effect of climatic variations on fishing effort has been analyzed using these three datasets.

To investigate the seasonal wind speed trends in Iskenderun Bay, a dataset comprising daily wind speed measurements was analyzed. This analysis utilizes data from the state meteorology institute’s Iskenderun Bay measurement center. The data specify the daily average wind speed and the prevailing wind direction among eight different directions.

Monthly average wind speeds were calculated for each month across the years using the following formula:

V_avg = (1/N) × Σ V_i

(1)

where V_avg is the average wind speed for the month, N is the number of days, and V_i is the wind speed on day i.

Seasonal trends were identified by aggregating data and applying linear regression to seasonal averages. The regression’s slope was calculated using:

$$\mathrm{\beta }=\mathrm{\Sigma }({\mathrm{X}}_{\mathrm{i}}-\overline{\mathrm{X}})({\mathrm{Y}}_{\mathrm{i}}-\overline{\mathrm{Y}})/\mathrm{\Sigma }{({\mathrm{X}}_{\mathrm{i}}-\overline{\mathrm{X}})}^2$$

(2)

where X_i is the year, Y_i is the seasonal average wind speed, and $\overline{\mathrm{X}}$, $\overline{\mathrm{Y}}$ are the mean values.

This methodology allowed for the analysis of wind speed variations over time, providing insights into the bay’s wind dynamics.

This dataset includes daily measurements of wind speed, direction, and duration between 2017 and 2023. The study encompasses the months of September, October, November, December, January, February, March, and April. In the data preprocessing stage, missing data were excluded from the analysis, and relevant variables were appropriately transformed. ‘Month’, ‘Year’, and ‘Direction’ variables were encoded as categorical factors, while ‘Intensity’ was treated as a continuous variable.

The primary objective of the study is to assess the impact of wind intensity on duration and to analyze how this effect varies with seasonal changes. In this context, a multiple linear regression model was employed to examine the relationship between wind intensity and duration, controlling for factors such as month, year, and direction. The model formulation is as follows:

Duration = β₀ + β₁ × Intensity + Σ (β_month × Month) + Σ (β_year × Year) + Σ (β_direction × Direction) + ε

(3)

where β₀ is the intercept, β₁ is the coefficient for wind intensity, β_month, β_year, and β_direction are the coefficients for the respective categorical variables, and ε is the error term.

The fit of the model was evaluated using R-squared and Adjusted R-squared values. Furthermore, F-statistics and p-values were used to test the significance of the model coefficients.

This study compares the changing monthly fishing effort durations, not only due to climatic conditions but also based on the hypothesis that it is related to fishing yields. Monthly catch amounts for these trawl fishing vessels were obtained from commercial fishing records. It is not possible to find daily catch amounts in these records because fishing vessels land their products every two or three days. In this process, the average monthly catch amount per vessel, in kilograms, has been evaluated from the records of 10 selected trawl fishing vessels over three years.

3. Results

The predominant wind directions in İskenderun Bay are primarily from the north (N) and east (E), with these directions typically showing higher average wind speeds across the year (Figure 1). The easterly winds are particularly strong in March, where they peak significantly higher than in other months, reaching up to about 14 m per second. This makes March the windiest month, especially from the east. The northerly winds also show high speeds, but they are more evenly distributed throughout the year compared to the easterly winds, maintaining relatively higher speeds in both the winter and spring months. In contrast, the southern (S) and western (W) winds are generally weaker and do not show dramatic peaks like the easterly winds. Figure 1 indicates that these directions maintain a more consistent, yet lower, average speed throughout the year. Thus, the windiest months in Iskenderun Bay tend to be from late winter to early spring, primarily driven by strong easterly and northerly winds. This pattern could be crucial for various applications, including maritime navigation and weather forecasting in the region.

A comprehensive statistical analysis of wind speed trends in Iskenderun Bay, based on an extensive evaluation of multi-year data, reveals significant seasonal fluctuations in wind velocity (Figure 2). During the summer months, wind speeds exhibit a clear upward trend, with average velocities increasing from approximately 5.2 m/s in early June to a peak of around 7.8 m/s by late August. This represents an approximate 50% increase in wind intensity, underscoring a substantial intensification in wind activity during the warmer period. Conversely, the winter months display a statistically significant decline in wind speeds, with average velocities decreasing from 6.5 m/s in November to approximately 4.1 m/s by the end of January. This 37% reduction highlights a seasonal weakening in wind force during the colder months. The transitional periods of spring and autumn demonstrate intermediate wind speeds, acting as a bridge between the high-intensity summer months and the low-intensity winter period, thus completing the annual cycle of wind variations in the bay.

The analysis of seven years of wind direction and intensity data further substantiates these seasonal variations, showing an increasing trend in wind strength during the summer months and a corresponding decline during autumn and winter. This seasonal fluctuation directly overlaps with the peak trawl fishing season, raising potential concerns regarding operational efficiency. Wind intensity naturally imposes limitations on all maritime activities, including trawl fishing. However, statistical evaluations indicate that despite periods of heightened wind speeds, specific areas within Iskenderun Bay remain suitable for trawl operations due to spatial variations in wind direction. Furthermore, calculations reveal that, despite fluctuations in wind intensity, a trawl fishing vessel can operate for an average of 16 h per 24 h period, with wind conditions causing only a 35% reduction in effective fishing hours. This suggests that while wind activity influences trawling efficiency, it does not significantly hinder overall fishing operations in the region. These findings provide valuable insights into the adaptive capacity of trawl fishers in Iskenderun Bay, ensuring continued economic viability despite meteorological challenges.

The analysis of trawl fishing activity in Iskenderun Bay (2017–2023) reveals clear seasonal trends in average daily sea duration, supported by statistical evaluations (Figure 3). In winter (January–February), a significant decline (p < 0.05) in sea duration was observed between 2017 and 2019, followed by a stabilization trend. This reduction is likely due to adverse weather conditions and seasonal fishing restrictions, which limit operational hours. Statistical tests indicate that mean fishing duration in January decreased from approximately 8.2 h in 2017 to 6.5 h in 2019, before stabilizing around 6.8 h in subsequent years. In spring (March–April), average fishing hours remained relatively stable at 9–10 h per day, showing low variability (standard deviation < 1.2 h). This suggests that favorable environmental conditions and fewer restrictions allow consistent trawling activity. Regression analysis indicates no significant long-term trend (p > 0.1) during this period, supporting operational stability. From September to December, a gradual increase in fishing duration is evident. In October and November, sea duration increased by approximately 15% over the study period, reaching an average of 10.2 h per day by 2023. This trend aligns with improved fishing conditions, changes in regulations, or the seasonal abundance of target species. Statistical modeling shows a positive correlation (R² = 0.67, p < 0.05) between fishing duration and seasonal factors, highlighting how fishermen extend their time at sea in response to improved conditions.

The shaded areas in each graph represent the statistical variability (standard deviation) in daily sea duration among trawl fishing vessels in İskenderun Bay (Figure 4). The data from the trawl fishing season in İskenderun Bay between 2021 and 2023 show significant monthly changes in total daily average catch amounts, species composition, and daily fishing effort duration. In September, the total daily catch was approximately 464.48 kg, with shrimp species contributing 133 kg (28.6%) and red mullet 97 kg (20.9%). The daily fishing effort duration was 10.29 h. In October, total catches reached their peak at 814.26 kg, representing a 75% increase from September. Shrimp and red mullet reached their highest levels at 179 kg (22%) and 158.83 kg (19.5%), respectively. Correspondingly, the fishing effort duration increased to 13.94 h, indicating that longer fishing times contributed to higher catch amounts. After October, both catch amounts and fishing durations started to decline. In November, total catches dropped by 42% to 471.49 kg, while the fishing duration decreased to 12.01 h. Shrimp catches fell significantly to 37.83 kg (8%), and red mullet declined to 77.75 kg (16.5%). The decline continued in December, with total catches decreasing to 296.73 kg and fishing effort duration slightly increasing to 12.53 h. In January, total catches further decreased to 238.19 kg, while the fishing effort duration reduced to 10.73 h. The downward trend persisted into February, where total catches dropped to 180.64 kg, marking a 77.8% decrease from the October peak. The fishing effort duration also decreased to 9.04 h. In March, a slight recovery occurred, with total catches rising to 200.95 kg and fishing effort duration decreasing to 7.79 h. This suggests that despite shorter fishing durations, certain species such as shrimp (56.25 kg) contributed to the temporary increase in catches. However, by April, total catches declined again to 173.65 kg, and fishing effort duration reached its lowest level at 6.47 h. There was a 78.6% reduction in total daily average catch amounts from the peak in October (814.26 kg) to the season’s end in April (173.65 kg). The daily fishing effort duration showed a similar pattern, decreasing by 53.6% from 13.94 h in October to 6.47 h in April. Therefore, April shows a narrow variability (low standard deviation), indicating consistent operation times with stable fishing conditions. In contrast, September exhibits wider variability (high standard deviation), suggesting greater fluctuations in fishing activity, likely due to variable fish availability or weather conditions. This dataset provides key insights into seasonal trends in fishing operations. The lower variability in spring months suggests stable fishing patterns, while the higher variability in autumn highlights adaptive changes in response to environmental and regulatory factors.

The regression analysis was performed on a dataset derived from daily average durations recorded for trawl fishing boats operating in Iskenderun Bay (Figure 5). This study aimed to understand the influence of wind intensity and direction on the operational durations of these boats, particularly considering various temporal aspects such as different months and years. The analysis revealed a significant negative relationship between wind intensity and the daily operational duration of trawl boats. Specifically, the regression model quantified that for each unit increase in wind intensity, the duration decreased by 0.367 h on average. This finding suggests that stronger wind conditions significantly reduce fishing operations, likely due to increased sea roughness or challenges in maneuvering the trawl nets (p < 0.001, 95% CI [−0.434, −0.300]).

Wind direction also played a critical role in affecting operational durations. East-southeast winds (ESE) were associated with a reduction in operation times, as indicated by a coefficient of −0.635, although this effect was not statistically significant (p = 0.196). Conversely, west-northwest winds (WNW) appeared to have a lesser negative impact, with a coefficient suggesting a slight increase in duration, again without statistical significance (p = 0.269) (

Table 1. Statistical analysis of monthly and annual variation in average trawl fishing durations in İskenderun Bay, with adjustments for wind intensity and direction, 2017–2023.

Variable	Coefficient	p-Value	95% CI Lower	95% CI Upper
Intercept	13.737	2.161 × 10−93	12.508	14.966
C(Month)[T.2]	−0.788	9.197 × 10−2	−1.704	0.129
C(Month)[T.3]	−1.115	1.409 × 10−2	−2.004	−0.225
C(Month)[T.4]	−4.045	3.438 × 10−17	−4.975	−3.114
C(Month)[T.9]	−0.129	7.870 × 10−1	−1.062	0.805
C(Month)[T.10]	3.838	3.994 × 10−17	2.953	4.723
C(Month)[T.11]	2.577	9.000 × 10−9	1.702	3.451
C(Month)[T.12]	2.500	1.816 × 10−8	1.633	3.366
C(Year)[T.2018]	1.457	4.637 × 10−4	0.642	2.272
C(Year)[T.2019]	0.032	9.392 × 10−1	−0.784	0.848
C(Year)[T.2020]	0.044	9.175 × 10−1	−0.781	0.868
C(Year)[T.2021]	0.235	5.740 × 10−1	−0.584	1.053
C(Year)[T.2022]	−2.039	2.881 × 10−5	−2.992	−1.086
C(Year)[T.2023]	−1.346	5.076 × 10−3	−2.287	−0.405
C(Direction)[T.ENE]	0.115	8.711 × 10−1	−1.270	1.499
C(Direction)[T.ESE]	−0.635	1.959 × 10−1	−1.599	0.328
C(Direction)[T.N]	0.441	4.287 × 10−1	−0.652	1.535
C(Direction)[T.NE]	−0.619	4.505 × 10−1	−2.229	0.990
C(Direction)[T.NNE]	−1.138	1.860 × 10−1	−2.824	0.549
C(Direction)[T.NNW]	−0.106	8.258 × 10−1	−1.048	0.837
C(Direction)[T.NW]	0.247	7.140 × 10−1	−1.073	1.566
C(Direction)[T.S]	−0.713	4.921 × 10−1	−2.748	1.322
C(Direction)[T.SE]	0.492	4.336 × 10−1	−0.740	1.724
C(Direction)[T.SSE]	0.830	3.497 × 10−1	−0.911	2.572
C(Direction)[T.SSW]	−0.430	6.222 × 10−1	−2.141	1.281
C(Direction)[T.SW]	−0.907	2.220 × 10−1	−2.363	0.549
C(Direction)[T.W]	−0.974	5.451 × 10−2	−1.968	0.019
C(Direction)[T.WNW]	1.120	2.688 × 10−1	−0.866	3.106
C(Direction)[T.WSW]	−0.627	2.054 × 10−1	−1.599	0.344
Wind Intensity	−0.367	1.882 × 10−26	−0.434	−0.301

). These results highlight the complex interactions between wind direction and fishing operations, where certain wind orientations may hinder or facilitate activities based on local geographical and oceanographic conditions. Seasonal analysis further enriched the understanding of operational dynamics, with months like October and November showing increased durations compared to January, the baseline month. The coefficients for October (+3.838) and November (+2.576) were statistically significant and indicated that operations tend to extend during these months, possibly due to favorable weather conditions or fishing cycles (95% CI for October [2.953, 4.723], for November [1.702, 3.451]).

Yearly fluctuations were also observed, with some years showing significant deviations from others. For example, the year 2022 displayed a notable decrease in operational duration, as reflected by a coefficient of −2.039, pointing to specific annual conditions that might have affected wind patterns, and subsequently, fishing operations (p < 0.001, 95% CI [−2.992, −1.085]). This detailed regression analysis provides vital insights into how environmental factors such as wind intensity and direction, alongside temporal variables, influence the operational durations of trawl fishing boats in Iskenderun Bay.

4. Discussion

In this study, the effects of changes in wind intensity and resulting waves on trawl fishing were examined. Significant changes in wind intensity are projected across the Middle East and Eastern Mediterranean. Meteorological data showed significant changes in wind intensity in Iskenderun Bay. Prevailing wind directions and daily average wind intensities vary seasonally in Iskenderun Bay, with stronger winds especially in summer. Strong winds and the resulting waves affect surface currents, limiting fishing activities. These effects can negatively impact fish farms and fishing operations [26]. The negative impacts of wind intensity on fishing limit operations and affect fishermen’s income. For example, small-scale fishermen in coastal Madagascar experienced a decrease of 21.7 fishing hours per year due to increased adverse weather [27]. Fishermen in Andhra Pradesh identified wind intensity as the most critical parameter affecting marine fishing, significantly impacting trawl fishing during adverse weather [28]. In Peninsular Malaysia, monsoon season wind and wave patterns negatively affected fishing operations and incomes [15]. The results of this study indicate that wind intensity increases during the summer months, while there is a general decreasing trend in wind intensity during the fishing seasons from 2017 to 2023. This can be attributed to the process of global climate change. This indicator suggests that during the process of global climate change, weather conditions may allow trawl fishing vessels to stay at sea for longer periods. The analysis of the impact of wind intensity on fishing duration in Iskenderun Bay highlights that southern and western winds are more effective than winds from other directions. This is because this part of the bay opens to the Mediterranean, causing waves from these directions to be higher and more impactful. Winds from other directions, even if stronger, do not create waves severe enough to restrict trawl fishing, especially in coastal areas.

The trawl fishing vessel fleet in Iskenderun Bay appears to number around 45. However, not all these boats exert the same fishing effort. There are differences in daily fishing hours, monthly sea outings, and seasonal fishing durations. These differences mainly arise from economic concerns and difficulties in finding fishing personnel [10]. To eliminate these differences, data from 15 actively working fishing boats were selected and monitored. This approach aims to understand variations due to climatic changes. However, it was found that the most significant factor in sea time was catch efficiency. We have estimated that demersal resources in Iskenderun Bay are under excessive fishing pressure because the fishing capacity in the region exceeds the ecosystem’s capacity. The main factor affecting fishing effort is economic reasons, particularly catch yield. Figure 4 and Figure 5 support these results. When the trawl fishing season opens, fishing effort increases. Over time, due to fishing pressure, fishing effort decreases in the later months of the season. By the end of the season, it drops to half of the initial values.

The duration of trawl fishing vessels’ time at sea in Iskenderun Bay is influenced by the catch efficiency of species [29]. Trawl fishing in Iskenderun Bay is carried out mostly in shallow waters up to 70 m. The catch includes various species, divided into fish, shrimp, and cephalopods. Shrimp fishing is generally carried out at night, while the same vessels target fish during the day, resulting in longer sea times [30]. When shrimp catch efficiency decreases, trawlers stay at sea only during the day, reducing sea time [31]. When examining the catch efficiency and sea time per individual fish, all species show a parallel relationship except sole, which has higher catch efficiency in spring. However, the economic impact of sole catch efficiency on sea time is not significant. Species that affect trawler sea time the most are red mullet, sea bream and lizardfish [32].

The effects of global climate change in Iskenderun Bay are increasingly noticeable in terms of fishing and environmental sustainability. The sustainability and effectiveness of efforts to manage the entry and establishment of invasive species require proactive, interactive, and reactive interventions that consider the changing conditions of local ecosystems [33]. Generally, the initial effects are negative for fishing. However, our study suggests that global climate change does not negatively affect the duration of fishing trips. In fact, it can be partially positive. During the autumn and winter months, there is a decrease in wind intensity due to climate change, reducing adverse sea conditions. In summer, wind intensity increases, but trawl fishing is banned in Iskenderun Bay during this period. Certainly, favorable weather conditions that may extend trawl fishing periods are expected to increase pressure on natural stocks in this fishing area due to overfishing. Can and Mazlum [34] stated that the impact of climate change is seen in rising sea temperatures and the abundance of migrant species, which negatively affects local fish stocks and fishing efficiency. Many researchers report that fishing in this bay, under heavy fishing pressure, is worsening economically and environmentally. Considering these changes, more comprehensive, dynamic, and ecosystem-sensitive management models should be applied in Iskenderun Bay, with increased monitoring and enforcement.

5. Conclusions

The effects of wind regime and intensity on trawl fishing efforts in İskenderun Bay and the Eastern Mediterranean are evident. These changes are likely to influence the fishing activities of the fishing vessels. However, these changes are making weather conditions more favorable for trawl fishing. These differences cause an increase in the intensity of westerly and southerly winds in the summer, while a decrease is observed during the winter months. In general, only westerly and southerly winds affect fishing efforts in Iskenderun Bay due to its geographical structure. In this context, no significant differences are expected in fishing activities during the autumn and winter seasons in İskenderun Bay. The main factor affecting the fishing efforts of trawl vessels and their duration at sea is the catch amount, which is indirectly affected by wind direction and intensity. In this region, demersal fish stocks are under intense fishing pressure, leading to high fishing activity at the beginning of the fishing season, typically in autumn. As the catch amount decreases, fishing activities significantly decline during the spring, even though it is still within the fishing season.