During the winter and spring of 2002 and 2003, we used time-integrated fertilization assays to monitor sperm availability in three populations of the green sea urchin Strongylocentrotus droebachiensis in Maine: a naturally occurring population of .40,000 urchins and two smaller groups (,1,000) of transplanted urchins isolated from other aggregations. Episodes of sperm release coincided in two p...

Available data on the reproductive biology of the Peruvian anchoveta (ElIgrauJis ringens, nonhem/caltral stock, 4-1405) are reviewed and lUed to estimate monthly spawning size and egg production iran January 1953 to December 1982. Basic information used are: (a) monthly biomass by length class (4 to 20 em), (b) a model relating the shape and position of the matUration ogive to sea surface tcnpe...

A deterministic, age-structured population model was developed to simulate potential management scenarios designed to increase growth of individuals (quantified by maximum length) in a hypothetical population of white perch, Morone americana (Gmelin). Four scenarios were developed that included non-selective mortality of adult white perch, increased mortality of age groups most influential on p...

Individuals migrate to exploit heterogeneities between spatially separated environments to modulate growth, survival, or reproduction. We devised a bioenergetics model to investigate the evolution of migration distance and its dependence on individual states. Atlantic cod Gadus morhua ranges from sedentary populations to stocks that migrate several thousand kilometers annually. We focused on th...

A reproductive analysis of 1225 specimens of Poeciliopsis gracilis obtained through monthly samples from Coatetelco, a tropical shallow lake in Central Mexico, was made. There was an evident sexual dimorphism, including a difference in body size at the onset of reproduction. Sex ratio deviated significantly from unity. Monthly variations in gonadosomatic (GSI), hepatosomatic (HSI) indexes and o...

In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) data and the multiple linear regression model were used to estimate distribution of biomass resources in 2010. The establishment of models, developed using different vegetation biomass sample data, normalized difference vegetation index (NDVI), leaf area index (LAI), meteorological data, coordinates, terrain data, and statisti...

In studies done a decade apart, we provide evidence of a recent shift toward a slower progression to sexual maturity as well as reduced egg production, especially among young, small female red snapper, in the Gulf of Mexico (Gulf). Slower maturation rates (among fish ≤6 years old), lower GSI values and decreased spawning frequency were observed, and were especially pronounced in the northwester...

  The population parameters and spawning season of the Spangeld emperor (Lethrinus nebulosus) were studied in coastal waters of Hormouzgan province. The monthly calculated mean values of gonadosomatic index (GSI) of females were indicate to increase from February, reach the highest in March and decline in June. The spawning season peak of L. nebulosus occurred in March. The Von Bertalanffy grow...