Juvenile fish survival is often strongly density dependent and results in relatively consistent average recruitment over a wide range of spawning stock biomasses. Hatching date-dependent mortality can limit contributions of individual hatching sub-cohorts (i.e., fish hatched in one period relative to another within the overall hatching distribution) to the year class and influence the potential...

the stimulatory effect of ovaprim, a commercial spawning inducing agent consisting of salmon gonadotropin releasing analogue (gnrha) and a dopamine d2- receptor antagonist, domperidone, was studied in doctor fish, garra rufa (heckel, 1843) under hatchery conditions. the feeding and rearing condition effects on the survival rate of naturally produced larvae were also evaluated. twenty-five fish ...

Atlantic bluefish exhibit cohort splitting, whereby two modes of juvenile recruits originate from spatially distinct springand summer-spawning regions in US Atlantic shelf waters. We evaluate the pattern of cohort splitting in a transition area (US Maryland coastal region and Chesapeake Bay) between the two major spawning regions. Spring and summer cohorts were differentially represented in Mar...

Despite the resolving power of DNA markers, pelagic and migratory marine fish species generally show very little geographical population structuring. In mackerel (Scomber scombrus L.) population differentiation has been detected only at a transatlantic scale. By applying two regions in mitochondrial DNA (mtDNA) (D-loop and cytochrome b (cytb)) in combination with genealogical and frequency-base...

One species of Hemichordata, Balanoglossus misakiensis, is then acorn worm originally reported from the intertidal zone of the Miura Peninsula on the Pacific Ocean side of Japan. We histologically examined the reproductive cycle of the population of this species, which inhabits only the sublittoral zone in the Sea of Japan. Testes and ovaries began to develop at the beginning of May 2003 and we...

Atlantic herring is an excellent species for studying the genetic basis of adaptation in geographically distant populations because of its characteristically large population sizes and low genetic drift. In this study we compared whole-genome resequencing data of Atlantic herring populations from both sides of the Atlantic Ocean. An important finding was the very low degree of genetic different...

Bighead carp (Hypophthalmichthys nobilis) have been introduced throughout Europe, mostly unintentionally, and little attention has been given to their potential for natural reproduction. We investigated the presence of young-of-the-year bighead carp in an irrigation canal network of Northern Italy and the environmental conditions associated with spawning in 2011-2015. The adult bighead carp pop...

Several years of research on the gametic development and spawning of different species of holothurians have produced results that find applications in aquaculture and fisheries management programs. The first set of data shows that sea cucumbers secrete a biologically active chemical which allows gamete synthesis synchrony among conspecifics. Laboratory experiments have revealed that the gametic...

Executive Summary This report presents the results of a 1-year preliminary study to investigate the size, age and reproduction of albacore caught in the Eastern tuna and Billfish Fishery (ETBF) on Australia's east coast. The objectives of the study were to provided early information on key biological parameters including length-weight conversions, sex ratios, spawning frequency, batch fecundity...

—We used an age-structured model to evaluate the impacts of recreational angling during spawning on populations of largemouth bass Micropterus salmoides and the potential benefits of seasonal fishing closures. We simulated fisheries with average and high capture rates (i.e., fractions of the stock caught by anglers). We manipulated mortality rates to mimic the effects of various regulations, in...