Fish use of Beaufort Sea coastal waters was examined during summer and winter periods 1977–80. Arctic cod (Boreogadus saida) were abundant but their occurrence was highly variable. They accounted for 8–78% of all fish caught in Simpson Lagoon during two summers, and 0.4–100% of catches at various coastal sites in winter. Arctic cod increased in abundance in the lagoon during late summer and some association was noted between their numbers and higher salinities but not temperature or turbidity. Some cod remained in shallow waters in early winter but deeper areas were used through the winter, and the highest catch rate was recorded 175 km offshore. Principal foods of the cod in nearshore waters were mysids (Mysis litoralis, M. relicta), amphipods (Onisimus glacialis), and copepods. The cod caught were generally small (60–170 mm) and young (ages 1–3). Most males matured at ages 2–3 and females at age 3. These size, age, and maturity characteristics indicate a life history strategy (r-selection) unlike that typified by many other arctic fish populations, particularly the freshwater and anadromous species which tend to be slow growing, late maturing and long-lived (K-selection).Key words: Arctic cod, Boreogadus saida; Beaufort Sea, distribution, life history strategy

SynopsisThis paper reviews current knowledge of substrate-associated juvenile Sebastes. In general, juvenile rockfish recruit to shallower depths than those occupied by conspecific adults. Habitat use by newly recruited rockfish differs markedly among species. While a few species recruit to shallow-dwelling macrophytes, such as Zostera, many others recruit to larger brown algae, such as Nereocystis and Macrocystis. A few deeper dwelling species recruit to low relief or soft substrata. However, little is known on recruitment of these deeper dwellers. Crustaceans are the major component of the diets of newly recruited Sebastes. Species which continue to forage in the water column shift to larger crustaceans (e.g. euphausids) and fish as they grow. Species which shift to substrate-associated prey soon begin to feed on larger algal-associated gammarid amphipods, shrimps and isopods. Field studies indicate variation in intraspecific growth rates over large geographic distances, among nearby sites and among algal habitats on the same reef, with food availability and water temperature being major factors in the differences. In particular, laboratory studies have shown that temperature is one of the most important factors in growth rates. Many species of juvenile rockfish make ontogenetic movements, often moving into deeper water as they age. Most seasonal movements appear to be related to changes in water temperature and turbulence.

No abstract

Recruitment for many marine fishes is believed to be determined at an early life history stage. Pacific herring (Clupea pallasi) spawn in the intertidal and shallow subtidal zones and have a demersal egg stage that is susceptible to egg removals during incubation. Data were collected by the Alaska Department of Fish and Game in four years in Prince William Sound, Alaska, to identify important factors contributing to egg removals. We constructed analysis of variance models based on physical and biological variables to determine which environmental factors control egg loss rates. The habitat variables examined at each study transect were depth, wave exposure, north-south location, substrate, vegetation, mean bird abundance, abundance of loose eggs, and fish predation. Depth of spawn was the primary factor determining egg loss. Cumulative time of air exposure over incubation was substituted into the model for depth. Using the model, the total estimated egg loss from spawning to hatching ranged from 67 to 100% with an average of 75% (SE = 3.3%) in 1995. Eggs were originally deposited from 4 to -6 m depth relative to mean low water. The majority of eggs that remained in the spawning beds to hatching were deposited from 1 to -4 m depth. Egg removals due to avian predation were probably responsible for extreme egg loss rates at shallow depths.

ABSTRACT. All five North American Pacific salmon species occur in small numbers in arctic waters, but only pink and chum salmon appear to have viable populations north of Point Hope, Alaska. Pink salmon are the most common species and constitute 85% of salmon caught in biological surveys. Pink salmon apparently have small runs in eight arctic drainages, while chum salmon may have small runs in six. Arctic pink salmon are smaller in size than individuals to the south but have similar meristic characteristics. It is likely that minimal use of freshwater habitats by pink and chum salmon has allowed them to colonize characteristically cold arctic rivers.