recently the previous caspian ecosystem is in a catastrophic condition which caused changes in the absolute and relative abundance of the commercially important caspian kutum (rutilus frisii kutum) in iranian waters. the paper presents estimates of yield-per-recruit and spawning biomass-per-recruit under various harvest strategies of fmax, f0.1, f30%. it proposes a method for estimating accepta...

Parametric relationships between recruitment and an index of parental stock size assume the latter is proportionally related to spawning potential (usually indexed by spawning biomass), irrespective of the demographic composition of adults. Recent empirical information, however, suggests that spawning by older, more experienced females is more successful than that by the young, small or inexper...

There have been recent changes in the Caspian Sea ecosystem, such as those due to changes in sea level or those caused by the invasive ctenophore, Mnemiopsis leidyi. It is believed that these changes had significant impacts on the absolute and relative abundance of the commercially important anchovy kilka (Clupeonella engrauliformis) and common kilka (C. cultriventris caspia) leading to decline...

Effects of age at first capture (tc) and fishing (F) as well as natural mortalities (M) on yield and biomass-per-recruit of tiger tooth croacker, Otolithes ruber were evaluated in the northwest of the Persian Gulf using the Beverton-Holt model. The yield-per-recruit (Y/R) was 175 (g/r), which was less than maximum yield-per-recruit value (217 (g/r)) at fishing mortality of 1 year-1. Current ...

The relationships between fecundity and size of Atlantic herring (Clupea harengus) were estimated within five different spawning areas off the coast Nova Scotia in 2019 2020. Statistically significant differences relative to body weight observed among years. Fecundity-at-length on German Bank ground was 29%–36% 22%–28% lower than estimates from 2001 1970, respectively. Temporal changes weight- ...

Manuscript accepted 17 August 1999. Fish. Bull. 98:75–85 (2000). Abstract.–For fish populations with an annual breeding cycle, a biological reference point based on the Leslie matrix is presented and compared with percent maximum spawning potential (%MSP) and Fmed reference points. For deterministic population projections, the reference point is defined as the level of fishing mortality (Fst) t...

The current harvest policy for the Pacific halibut fishery uses a 32-inch minimum size limit in the directed commercial fishery, and total annual catches in each of the eight regulatory areas are based on area-specific exploitation rate targets. In nondirected fisheries retention of halibut is prohibited. Post-release survival rates are gear dependent and partially based on observer accounts of...