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modelling study of the influence of environment and food supply on survival of Crassostrea gigas larvae. e ICES Journal of Marine Science, 61: 596e616. A biochemically based model was developed to simulate the growth, development, and metamorphosis of larvae of the Pacific oyster (Crassostrea gigas). The unique characteristics of the model are that it: (1) defines larvae in terms of their protein, neutral lipid, polar lipid, carbohydrate, and ash content; (2) tracks weight separately from length to follow larval condition; and (3) includes genetic variation in growth efficiency and egg quality to better simulate cohort population dynamics. The model includes parameterizations for filtration, ingestion, and respiration, which determine larval growth rate, and processes controlling larval mortality and metamorphosis. Changes in larval tissue composition occur as the larva grows and in response to the biochemical composition of the food.Simulations of larval growth indicate that departures of temperature, salinity, or food content from optimum levels reduce larval cohort survival, either because of metabolic constraints that result in death, unsuccessful metamorphosis, or increased predation resulting from increased larval lifespan. Temperatures and salinities near optimal values improve larval survival at low food concentration by increasing ingestion rate or growth efficiency. Also, survival at a given food concentration can vary widely depending on food composition, which determines food quality. The simulations suggest that the ratio of carbohydrate + lipid-to-protein may best describe the overall food quality, with optimal food compositions being characterized by ratios near 1.2 to 1.4 over a range of food concentrations. In contrast, food compositions containing too much or too little protein reduce larval survival, even at saturating food concentrations.In simulations emphasizing genetic variability within the cohort, larvae with high growth efficiency originating from large eggs out-perform other egg qualityegrowth efficiency combinations over a wide range of temperature, salinity, and food contents. As a consequence, suboptimal temperature, salinity, or food content compresses genetic variation by uniformly favouring larvae from large eggs with a high growth efficiency. However, the larval survival obtained from simulations that use a range of food qualities is representative of a much broader range of genetic types. Thus, the simulations support the supposition that food quality is an important variable controlling the survival and genetic variability of C. gigas larval cohorts.

Female summer flounder Paralichthys dentatus grow faster than males and experience a lower natural mortality rate. Sex‐structured assessment models have been developed for other fishes with sexually dimorphic characteristics to better account for population dynamics. Although a desire exists to develop similar assessment techniques for summer flounder, some prerequisite data are not available, including the sex of fish that are landed in the recreational fishery. Furthermore, summer flounder recreational landings are constrained within harvest limits almost entirely by minimum size restrictions—a management approach that could place much of the recreational fishing mortality on females. To fill a basic but important data requirement to improve the stock assessment of this species while also providing some insight on how current management strategies might impact the sex structure of the population, we collected data on sex and length of summer flounder (n = 4,437) that were landed in the New Jersey recreational fishery in 2009 and 2010. Females dominated the recreational catch in both years (95% female overall). The proportion of landed fish at a given length that were females was greater at lower latitudes and earlier in the summer; the proportion female at length was greater in 2010 than in 2009. Extensive seasonal, annual, and spatial variability evident over such a local scale suggests a highly dynamic sex dependency in the population dynamics of summer flounder and indicates that a more robust data set covering wider geographic and temporal scales will be necessary before sex‐specific landings data can be confidently incorporated into an assessment. Received February 20, 2012; accepted August 17, 2012

Models that account for sex‐specific behavior and population dynamics are becoming more common in the stock assessment of sexually dimorphic fishes. However, such models can be data intensive and require some knowledge or assumptions about the sex ratio of fishery landings. A recent stock assessment review of Summer Flounder Paralichthys dentatus identified the need to account for sex‐specific fishing mortality in the assessment model; however, no data on the sex composition of the catch were available. Fishery‐independent, sex‐specific information for this species is collected annually by the National Marine Fisheries Service's Northeast Fisheries Science Center during their bottom trawl survey. Sex at age from the survey could be applied to the fishery landings if the probability of landing a given sex at a given age is equivalent for fish collected by the survey and those in the landings. To generate the first regionally comprehensive database on the sex ratio of Summer Flounder landings and to determine the efficacy of using survey sex‐at‐age keys to estimate the sex of landed fish, we recorded the sex composition of the commercial and recreational catches of Summer Flounder (n = 31,912) in 2010 and 2011. When (1) trawl survey length data were left‐truncated to simulate the minimum retention sizes in the fisheries and (2) age–length keys generated from fishery‐dependent data were applied to length frequency distributions from the survey to simulate the growth rates of landed fish, the sex‐at‐age pattern in the survey‐derived data closely resembled the patterns in the catch. However, statistically significant differences in sex at age remained between the catch and the survey‐derived data. We hypothesize that these differences are attributable to differences in the spatiotemporal distributions of the sexes and of the survey and fishing effort. Received March 9, 2015; accepted June 23, 2015

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