Search

Abstract: Hatchery programs involving the mass release of artificially propagated fishes have been implemented worldwide. However, few studies have assessed whether hatchery programs actually increase the net population growth of [...]

Many studies have reported density‐dependent growth in single species, but density‐dependent growth can also occur between species when overlap in resource use occurs. We interrogate long‐term (1972–2010) monitoring data from the Bering Sea for evidence of intra‐ and interspecific density‐dependent growth among three species of Pacific salmon: sockeye, chum and pink. Partial correlation analysis, using intraspecific density as a control variable, identified interspecific density‐dependent growth among these three salmon species. As growth condition affects maturation, the maturity rates also depend on intra‐ and interspecific densities. Pacific salmon in the Bering Sea are of mixed origin, from North American and Asian rivers. As salmon return to their natal rivers, density‐dependent effects on their ocean growth and maturity during migration might have cascading effects on salmon returning to each continent, as salmon‐derived nutrients play important roles in riparian and terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

A study aims to relate causes of intrapopulational variation in the maturation schedule of chum salmon (Oncorhynchus keta) to previous growth history and to evaluate the effect of variation in growth history on the probabilistic reaction norm for maturation. Results indicate that the most recent growth condition is the most important factor affecting whether a fish matured during the subsequent breeding season and that the relationship between body size and maturation probability could be plastically modified by growth history.

The North Pacific spiny dogfish (SPD), Squalus suckleyi, is a commercially exploited shark species that plays an important role in the ecosystem. To elucidate the distribution of the SPD in the North Pacific and to evaluate the effects of sea surface temperature (SST) and prey availability on its distribution, we estimated the probability of SPD presence using a generalized additive model with a binomial error distribution from SPD presence/absence data on 14,824 operations in fisheryindependent gillnet surveys between 1972 and 2011. The habitat model was structured in the east and west to reflect differences in the North Pacific oceanic environments. In the east, a higher probability of SPD presence was identified along the coast from the eastern Gulf of Alaska to Queen Charlotte Sound. In the west, it was identified around northern Japan. The estimated distribution was continuous between the two areas, whereas the probability of SPD presence was relatively low. Although the probability of SPD presence was higher at SSTs between 6°C and 12°C, the SST at the peak probability of SPD presence differed between the west and east. The prey species, Japanese sardine, Sardinops melanostictus, and walleye pollock, Gadus chalcogrammus, in the west and boreal clubhook squid, Onychoteuthis borealijaponica, in the east significantly affected the probability of SPD presence, which was higher if the prey species co-existed with SPD. Therefore, SPD might adapt their distribution to that of available prey species. SPD stock assessment and management in these two important areas are required for its sustainable utilization. [ABSTRACT FROM AUTHOR]

Ref: Can. J. Aquat. Sci. 63: 55-62 (2006). On page 59, there was an error in the Fig. 2 caption: the bar descriptions were inadvertently reversed for natural spawning and [...]

The article focuses on a study conducted following reports of high air pollutants in form of heavy metals getting collected by seabirds. Four species of seabirds Fratercula corniculata, Uria lomvia, Puffinus tenuirostris and Fulmarus glacialis were studied and metal accumulation in their tissues were recorded. Aerial differences in metal accumulation of these birds and Sea gulls were done and it was observed that Gulls had high levels of Cadmium and mercury.