Growth and Condition of Largemouth Bass (Micropterus nigricans) and Bluegill (Lepomis macrochirus) in a Minnesota, USA, Lake with Separate Dredged and Non-Dredged Basins

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript is well written and provides useful information for the management of inland lake fisheries and their habitats; especially in terms of understanding benefits of habitat restoration/enhancement actions. My following editorial comments are relatively minor.

Introduction 

lines 51-54: were the two study species simply selected because they are important gamefish? or is there an additional biological rationale, such as trophic position (zooplantivore/invertivore vs. carnivore/piscivore)?

lines 57-59: please provide some more details that describe the improvements to game fish community. Did this include changes to the available prey resources (see lines 94-95 regarding stunted prey fishes)?

Methods:

Field work, lines 98-100: were collections done at on the same days for each basin, or separate? any rationale for late season sampling?

Lines 75-77. Can the authors provide any information regarding the movements of fishes between east and west basin? Any implications of the movements of individuals between basins on study findings (for the discussion)?

Lab work:

Were scales interpreted by one or multiple readers?

Please state the expected bias of using scales to interpret ages of Bluegill and Largemouth bass, or in comparison to lethally obtained calcified structures.

lines 111 and 116 - My preference is to use the term interpreted over determined, as that is what the reader is doing.

Data Analysis:

lines 101 and 121-122. This approach assumes no sex-specific variation in growth and mass. Should state that is the assumption here, and also identify past studies that have shown sex-specific differences in growth for North American Largemouth bass populations (e.g. Schramm and Smith 1987 Proc. Annu. Cont. Southeast Assoc. Fish and Wildl. Agencies 41 :76-84) and for Bluegill. Bias in results associated with pooling an unknown ratio of males and females together?  

For the statistical tests, were associated assumptions tested? Also, what statistical software (R-code? or other) was used to analyze data and fit growth curves?

Discussion

Lines 304-316: Could the lack of older individuals simply be associated with the limitation of using scales to interpret the ages of older bass, as compared to pectoral fin rays and otoliths?

Conclusions:

Lines 381-389: Given that an open connection between the 2 basins exists, a movement study would help to understand whether there are 2 sub-populations associated with each basin or if enough mixing of individuals occurs that it functions as a single population.   

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

The manuscript assessed the growth rates and body conditions of two common fish species, largemouth bass and bluegill, subjected to recreational fishing, in Lake Winona, USA. Historical data, spanning 19 years before and 15 years after the partial dredging of the eastern part of the lake basins, are used to assess pre- and post-dredging growth of the above-mentioned fish species.

The manuscript is well composed, with a sampling strategy that permits comparisons between the basins, as well as with the incorporation of historical data and application of standard statistical methods.

One of the main points I would like to emphasize is the need for the reader to gain a deeper understanding of the physical, chemical, and biological differences that may exist between the eastern and western sections of the lake, including differences in nutrient loadings and sources, as well as fishing levels. Such information might be important for understanding the results, and I recommend including a paragraph in the Introduction section, with further elaboration in the Discussion section, that summarizes the other potential impacts on fish growth, at least during the autumn season when the sampling took place.

Another suggestion is to more clearly differentiate between the historical changes (pre- and post-dredging data) versus the current differences of fish growth and condition between basins in the Discussion section. 

 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents comparative study of growth rates of two North-American freshwater fish species in two (conditionally) hydrologically separated parts of a large lake Wenona, Minnesota (US), after dredging of one part. Fish size and age, relative weight, back-calculated lengths were obtained and discussed. Thus, two water bodies (with different conditions) were studied and compared. The comparison of two water bodies is correct and the conclusions are accurate for this case study, but not enough for a possible statistically valid conclusion of general relations to be applied to other NA water bodies (and populations of the studied fish) in general.

 Introduction section will benefit from the addition of review of literature information on seasonal and annual moving of the studied fish species within a water body or between water bodies.

 I have several remarks on Method section. Clarification is necessary for description of all hydrological connections of the studied two parts of Wenona with Mississippi River, local streams, lakes as well as assessment of possible fish exchange between two studied parts of Wenona because fish migrations/moving could influence to results and conclusions of the current study.

Please, provide necessary details concerning fish sampling: what parts of water bodies were used as collection points? How many points (localities)? Fish individuals of different size classes are distributed non-randomly within large water bodies. Therefore, sampling of 1 or 2 localities within a large water body will not enough for gathering representative data.

Authors provided reasonable explanation of their method approaches. Nevertheless, fish otoliths are currently accepted as more reliable age-registration structure comparing to scales. Additionally, what about standardization of procedures with scales? In other words, which sector of a scale was used for back calculation of length?

 Discussion section. There is theoretical possibility that fish individuals of a certain age or size prefer and choose appropriate parts of a water body or move in appropriate hydrologically connected water bodies: e.g., small-sized individuals prefer vegetated non-dredged part and large-sized individuals move to deeper open waters. Theoretically, individuals with different growth rates could have different strategies of spatial distribution. Assessment of probable fish exchange between water bodies are desirable in the text. Please, how authors can separate residential vs migrant fish individuals collected in the two parts of Wenona?

 Conclusion section. Please, exclude literature references from conclusion section and focus on main original results of the current study. Comparison with literature sources are more appropriate in the Discussion section. The text with documentation of “Additional studies … are needed…”, “We suggest future efforts…” is not very good as man conclusions from the results. The same is true for reference to “N. Mundhal, unpublished data”. This is ok in Discussion but not here. In the conclusion section, please, focus on the novelty of your study and emphasise most reasonable conclusions which may be useful for researchers who investigate other populations of bluegill and bass outside Wenona.

 Despite some comments, in general, the manuscript may be useful contribution to understanding processes in recently renovated Wenona Lake, MN, and may be reconsidered for publication in Limn Review after a major revision.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

I am grateful to the authors for corrections to the text and, most importantly, for detailing the situation and adding details to the methodology, making the manuscript more open and honest.