The importance of spawning behavior in understanding the vulnerability of exploited marine fishes in the U.S. Gulf of Mexico

The vulnerability of a fish stock to becoming overfished is dependent upon biological traits that influence productivity and external factors that determine susceptibility or exposure to fishing effort. While a suite of life history traits are traditionally incorporated into management efforts due to their direct association with vulnerability to overfishing, spawning behavioral traits are seldom considered. We synthesized the existing biological and fisheries information of 28 fish stocks in the U.S. Gulf of Mexico to investigate relationships between life history traits, spawning behavioral traits, management regulations, and vulnerability to fishing during the spawning season. Our results showed that spawning behavioral traits were not correlated with life history traits but improved identification of species that have been historically overfished. Species varied widely in their intrinsic vulnerability to fishing during spawning in association with a broad range of behavioral strategies. Extrinsic vulnerability was high for nearly all species due to exposure to fishing during the spawning season and few management measures in place to protect spawning fish. Similarly, several species with the highest vulnerability scores were historically overfished in association with spawning aggregations. The most vulnerable species included several stocks that have not been assessed and should be prioritized for further research and monitoring. Collectively, the results of this study illustrate that spawning behavior is a distinct aspect of fish ecology that is important to consider for predictions of vulnerability and resilience to fisheries exploitation

The influence of sample distribution on growth model output for a highly-exploited marine fish, the Gulf Corvina (Cynoscion othonopterus)

Estimating the growth of fishes is critical to understanding their life history and conducting fisheries assessments. It is imperative to sufficiently sample each size and age class of fishes to construct models that accurately reflect biological growth patterns, but this may be a challenging endeavor for highly-exploited species in which older fish are rare. Here, we use the Gulf Corvina (Cynoscion othonopterus), a vulnerable marine fish that has been persistently overfished for two decades, as a model species to compare the performance of several growth models. We fit the von Bertalanffy, Gompertz, logistic, Schnute, and Schnute–Richards growth models to length-at-age data by nonlinear least squares regression and used simple indicators to reveal biased data and ensure our results were biologically feasible. We then explored the consequences of selecting a biased growth model with a per-recruit model that estimated female spawning-stock-biomass-per-recruit and yield-per-recruit. Based on statistics alone, we found that the Schnute–Richards model described our data best. However, it was evident that our data were biased by a bimodal distribution of samples and underrepresentation of large, old individuals, and we found the Schnute–Richards model output to be biologically implausible. By simulating an equal distribution of samples across all age classes, we found that sample distribution distinctly influenced model output for all growth models tested. Consequently, we determined that the growth pattern of the Gulf Corvina was best described by the von Bertalanffy growth model, which was the most robust to biased data, comparable across studies, and statistically comparable to the Schnute–Richards model. Growth model selection had important consequences for assessment, as the per-recruit model employing the Schnute–Richards model fit to raw data predicted the stock to be in a much healthier state than per-recruit models employing other growth models. Our results serve as a reminder of the importance of complete sampling of all size and age classes when possible and transparent identification of biased data when complete sampling is not possible

Reproductive Biology and Evolution of Epinephelid and Serranid Fishes (Perciformes, Epinephelidae, Serranidae)

Teleost fishes exhibit an unrivaled diversity of reproductive patterns compared to other vertebrates, and the groupers (Epinephelidae) and seabasses (Serranidae) represent an extreme example of this diversity, because significant variations in sexual pattern, mating behavior, and reproductive anatomy occur among species in both families. For this research, I investigate these three aspects of the reproductive biology in five species of groupers from the eastern Pacific. I then combine my data with published results on the reproductive biology of other groupers and seabasses to describe taxonomic differences in these aspects and reconstruct their evolutionary history. Finally, I use a comparative phylogenetic approach to evaluate the evolutionary relationship between mating system characteristics (i.e., mating group structure and sperm competition) and sexual pattern. More specifically, I test whether evolutionary shifts in sexual pattern and, in particular the loss of sex change, were influenced by changes from paired to group spawning and associated increases in sperm competition among males. These analyses allow me to determine whether predictions of sex-allocation theory regarding the influence of mating behavior on sex allocation are congruent with fine-scale, evolutionary patterns of sex change within a resolved phylogeny.My results indicate that characteristics of the sexual pattern, mating behavior, and reproductive anatomy in both families are exceptionally labile. Evolutionary transformations in these features do not strictly follow taxonomic lines and remarkable changes have evolved in closely related species and genera. The most parsimonious phylogenetic reconstructions of the evolutionary history of sexual patterns indicate that protogynous hermaphroditism is the ancestral character state in both the Epinephelidae and the Serranidae, and other forms of hermaphroditism evolved secondarily from this state. Tests of correlated evolution showed that evolutionary transformations in sexual pattern from protogyny to gonochorism are correlated with transformations in mating group structure from paired to group spawning, and sperm competition is significantly higher in gonochoric species than protogynous species. These results suggest that the loss of sex change was influenced by changes from paired to group spawning and associated increases in sperm competition among males. More importantly, this research provides phylogenetic support for predictions of the size-advantage model and empirical evidence for the influence of sperm competition on sex allocation in animals

Reproductive Biology and Evolution of Epinephelid and Serranid Fishes (Perciformes, Epinephelidae, Serranidae)

Teleost fishes exhibit an unrivaled diversity of reproductive patterns compared to other vertebrates, and the groupers (Epinephelidae) and seabasses (Serranidae) represent an extreme example of this diversity, because significant variations in sexual pattern, mating behavior, and reproductive anatomy occur among species in both families. For this research, I investigate these three aspects of the reproductive biology in five species of groupers from the eastern Pacific. I then combine my data with published results on the reproductive biology of other groupers and seabasses to describe taxonomic differences in these aspects and reconstruct their evolutionary history. Finally, I use a comparative phylogenetic approach to evaluate the evolutionary relationship between mating system characteristics (i.e., mating group structure and sperm competition) and sexual pattern. More specifically, I test whether evolutionary shifts in sexual pattern and, in particular the loss of sex change, were influenced by changes from paired to group spawning and associated increases in sperm competition among males. These analyses allow me to determine whether predictions of sex-allocation theory regarding the influence of mating behavior on sex allocation are congruent with fine-scale, evolutionary patterns of sex change within a resolved phylogeny.My results indicate that characteristics of the sexual pattern, mating behavior, and reproductive anatomy in both families are exceptionally labile. Evolutionary transformations in these features do not strictly follow taxonomic lines and remarkable changes have evolved in closely related species and genera. The most parsimonious phylogenetic reconstructions of the evolutionary history of sexual patterns indicate that protogynous hermaphroditism is the ancestral character state in both the Epinephelidae and the Serranidae, and other forms of hermaphroditism evolved secondarily from this state. Tests of correlated evolution showed that evolutionary transformations in sexual pattern from protogyny to gonochorism are correlated with transformations in mating group structure from paired to group spawning, and sperm competition is significantly higher in gonochoric species than protogynous species. These results suggest that the loss of sex change was influenced by changes from paired to group spawning and associated increases in sperm competition among males. More importantly, this research provides phylogenetic support for predictions of the size-advantage model and empirical evidence for the influence of sperm competition on sex allocation in animals

Color Patterns and Associated Behaviors in the Kelp Bass, Paralabrax clathratus (Teleostei: Serranidae)

Volume: 104Start Page: 45End Page: 6

Observations of spawning in the Leather Bass, Dermatolepis dermatolepis (Teleostei: Epinephelidae), at Cocos Island, Costa Rica

Courtship and spawning behavior is described for the Leather Bass, Dermatolepis dermatolepis, from observations made from a manned submersible at Cocos Island, Costa Rica on 19 days between November 2006 and February 2007. Spawning occurred in the evening (16:00–18:30 h) in subgroups of 10–32 individuals that formed within aggregations of 50–70 individuals. The mating sequence was characterized by subgroup formation and crowding behavior followed by a brief vertical spawning rush, gamete release, and the rapid separation of participants. The aggregation was present on all dives, and spawning was not restricted to specific lunar phases

Observations of spawning in the Leather Bass, Dermatolepis dermatolepis (Teleostei: Epinephelidae), at Cocos Island, Costa Rica

Courtship and spawning behavior is described for the Leather Bass, Dermatolepis dermatolepis, from observations made from a manned submersible at Cocos Island, Costa Rica on 19 days between November 2006 and February 2007. Spawning occurred in the evening (16:00–18:30 h) in subgroups of 10–32 individuals that formed within aggregations of 50–70 individuals. The mating sequence was characterized by subgroup formation and crowding behavior followed by a brief vertical spawning rush, gamete release, and the rapid separation of participants. The aggregation was present on all dives, and spawning was not restricted to specific lunar phases