Herring in the study area school above the krill at Krill antipredator behaviour includes a flexible Herring in the study area school above the krill at Krill antipredator behaviour includes a flexible day, schools disperse at night and herring then DVM pattern, apparently responding to the day, schools disperse at night and herring then DVM pattern, apparently responding to the forage on vertically migrating krill. Nocturnal presence of fish. They partly remain below forage on vertically migrating krill. Nocturnal presence of fish. They partly remain below predation is probably visual, and seems to be visually foraging pelagic fish at day, but may predation is probably visual, and seems to be visually foraging pelagic fish at day, but may restricted to the upper 20-30 m. The non- avoid the near-bottom zone in presence of restricted to the upper 20-30 m. The non- avoid the near-bottom zone in presence of schooling whiting lives deeper than herring, demersal fish. In waters devoid of nocturnally schooling whiting lives deeper than herring, demersal fish. In waters devoid of nocturnally occupying the same depth range, and performing foraging planktivores, vertically migrating krill occupying the same depth range, and performing foraging planktivores, vertically migrating krill a similar diel migration pattern to that of krill. ascend all the way to the surface. while they a similar diel migration pattern to that of krill. ascend all the way to the surface. while they They forage on krill throughout the diel cycle. modify their DVM pattern and largely avoids the They forage on krill throughout the diel cycle. modify their DVM pattern and largely avoids the Prey search may be visual both day and night, upper 20-30 m at night in waters with abundance Prey search may be visual both day and night, upper 20-30 m at night in waters with abundance and whiting appears to be able to forage at lower of nocturnally foraging fish. Antipredator and whiting appears to be able to forage at lower of nocturnally foraging fish. Antipredator light intensities (i.e. deeper water) than herring. behaviour also constitutes instantaneous escape light intensities (i.e. deeper water) than herring. behaviour also constitutes instantaneous escape Norway pout is semi-demersal, largely remaining responses upon encounters with fish. The talk Norway pout is semi-demersal, largely remaining responses upon encounters with fish. The talk associated with the bottom at day, migrating into also addresses how more subtle mechanisms like associated with the bottom at day, migrating into also addresses how more subtle mechanisms like the water column at night. They forage on krill modification of feeding and swimming behaviour the water column at night. They forage on krill modification of feeding and swimming behaviour by day where the bottom intercepts the krill in response to mortality risks may be studied in by day where the bottom intercepts the krill in response to mortality risks may be studied in daytime habitat, otherwise predation is nocturnal the field. I argue that acoustic studies, daytime habitat, otherwise predation is nocturnal the field. I argue that acoustic studies, by vertically migrating individuals ascending into comprising acoustic target tracking of individual by vertically migrating individuals ascending into comprising acoustic target tracking of individual the water column. Norway pout has large eyes, plankters and fish, hold yet unexploited the water column. Norway pout has large eyes, plankters and fish, hold yet unexploited and may forage visually in relatively deep water opportunities for studies of fish-krill interactions and may forage visually in relatively deep water opportunities for studies of fish-krill interactions at day. Their swimming behaviour, hanging and for understanding of both krill and fish at day. Their swimming behaviour, hanging and for understanding of both krill and fish motionless in the water column, does, however, behaviour. motionless in the water column, does, however, behaviour. suggest that they may be ambush feeders by suggest that they may be ambush feeders by night. night.
Euphausiids and western Bering Sea herring feeding Euphausiids and western Bering Sea herring feeding
Nikolai I. Naumenko Nikolai I. Naumenko Kamchatka Research Institute of Fisheries and Oceanography (KamchatNIRO), 18 Kamchatka Research Institute of Fisheries and Oceanography (KamchatNIRO), 18 Naberezhanya Street, Petrapavlovsk, Russia 683602. E-mail: [email protected] Naberezhanya Street, Petrapavlovsk, Russia 683602. E-mail: [email protected]
The paper is based on long-term information seasons, areas, age cohorts. The herring diet The paper is based on long-term information seasons, areas, age cohorts. The herring diet (1939-1998) from weight method examination of (excluding the larval stages) contains 70 species (1939-1998) from weight method examination of (excluding the larval stages) contains 70 species 2997 stomach content from 117 coastal stations in of marine animals from 13 classes. The 2997 stomach content from 117 coastal stations in of marine animals from 13 classes. The Karaginsky Bay, Olyutorsky Bay, Olyutorsky- dominant prey is copepods which make up more Karaginsky Bay, Olyutorsky Bay, Olyutorsky- dominant prey is copepods which make up more Navarin area, and 1486 stomach examinations at than a half (51.7%) of the annual ration. The Navarin area, and 1486 stomach examinations at than a half (51.7%) of the annual ration. The 9 daily stations. Rations were calculated in three portion of euphausiids in the diet fluctuates 9 daily stations. Rations were calculated in three portion of euphausiids in the diet fluctuates ways: (1) using daily station data; (2) a annually from 9.8% to 70.7% with average value ways: (1) using daily station data; (2) a annually from 9.8% to 70.7% with average value physiological method using the well-known 42.1%. In May – September the herring feed physiological method using the well-known 42.1%. In May – September the herring feed Vinberg equation; and (3) our identification of a mainly on copepods – from 49.9% in September Vinberg equation; and (3) our identification of a mainly on copepods – from 49.9% in September strong dependence between daily ration, body to 88.4% in July. During other months, strong dependence between daily ration, body to 88.4% in July. During other months, weight, stomach fullness index, and water euphausiids contribute 68-88% of the stomach weight, stomach fullness index, and water euphausiids contribute 68-88% of the stomach temperature. contents. temperature. contents.
Food composition and trophic activity by Korfo- The variability of the herring diet is related to age Food composition and trophic activity by Korfo- The variability of the herring diet is related to age Karaginsky herring are very labile among years, composition. Through summer and autumn, age Karaginsky herring are very labile among years, composition. Through summer and autumn, age
113 113 0+ to age 2+ individuals are found mainly in the younger fish feed on copepods. 0+ to age 2+ individuals are found mainly in the younger fish feed on copepods. Karaginsky Bay; age 3+ in Olyutorksy Bay, and Karaginsky Bay; age 3+ in Olyutorksy Bay, and age 4+ to age 7+ are adjacent to the Koryak The annual consumption of euphausiids by the age 4+ to age 7+ are adjacent to the Koryak The annual consumption of euphausiids by the Coast/Elder. Herring reach Far Eastern areas population is from 1.3 (depressed condition) to Coast/Elder. Herring reach Far Eastern areas population is from 1.3 (depressed condition) to and during periods of high abundance, they 8.7 (high stock abundance) million tonnes. On and during periods of high abundance, they 8.7 (high stock abundance) million tonnes. On inhabit offshore waters. Diet composition is in average, each individual feeds from 0.39 kg inhabit offshore waters. Diet composition is in average, each individual feeds from 0.39 kg high conformity with habitat: 4-year-old and (32,000 individuals) to 0.54 kg (45,000 high conformity with habitat: 4-year-old and (32,000 individuals) to 0.54 kg (45,000 older individuals feed more on euphausiids while individuals) of these class organisms. older individuals feed more on euphausiids while individuals) of these class organisms.
Interactions Between Fish and Euphausiids and Potential Relations to Climate and Interactions Between Fish and Euphausiids and Potential Relations to Climate and Recruitment Recruitment
David M. Checkley, Jr. David M. Checkley, Jr. Marine Life Research Group, Scripps Institution of Oceanography, La Jolla, CA 93093-0218, Marine Life Research Group, Scripps Institution of Oceanography, La Jolla, CA 93093-0218, U.S.A. E-mail: [email protected] U.S.A. E-mail: [email protected]
The interaction of euphausiids and fish is abundant along the inner edge of the California The interaction of euphausiids and fish is abundant along the inner edge of the California complex. Each at times may be the predator, Current, north of Point Conception, in waters complex. Each at times may be the predator, Current, north of Point Conception, in waters prey, or competitor of the other. However, characteristic of isopycnal shoaling. Anchovy prey, or competitor of the other. However, characteristic of isopycnal shoaling. Anchovy certain interactions may be dominant. Here, I eggs were in water upwelled either recently certain interactions may be dominant. Here, I eggs were in water upwelled either recently present preliminary data consistent with one such (cool) or in the past (warmed), mostly south of present preliminary data consistent with one such (cool) or in the past (warmed), mostly south of interaction, predation by euphausiids on sardine Pt. Conception. An analogous cruise in March interaction, predation by euphausiids on sardine Pt. Conception. An analogous cruise in March and anchovy eggs in the California Current 1997 yielded very similar results. and anchovy eggs in the California Current 1997 yielded very similar results. Region. Region. Despite sampling caveats, including possible Despite sampling caveats, including possible High resolution maps of near-surface distributions avoidance of the near-surface intake of the High resolution maps of near-surface distributions avoidance of the near-surface intake of the of euphausiids and the eggs of the Pacific sardine CUFES pump by euphausiids and diel variation of euphausiids and the eggs of the Pacific sardine CUFES pump by euphausiids and diel variation (Sardinops sagax) and northern anchovy in their surface residence, the patterns of sardine (Sardinops sagax) and northern anchovy in their surface residence, the patterns of sardine (Engraulis mordax) were made during CalCOFI and anchovy eggs and euphausiids were (Engraulis mordax) were made during CalCOFI and anchovy eggs and euphausiids were cruise 9603JD using the Continuous, Underway complementary during CalCOFI cruise 9603JD. cruise 9603JD using the Continuous, Underway complementary during CalCOFI cruise 9603JD. Fish Egg Sampler, CUFES (Checkley et al. The figure below shows that sardine eggs were Fish Egg Sampler, CUFES (Checkley et al. The figure below shows that sardine eggs were 1997, in press). This device collects eggs of fish abundant only in the absence of euphausiids and 1997, in press). This device collects eggs of fish abundant only in the absence of euphausiids and from 3-m depth continuously during a survey by vice versa. from 3-m depth continuously during a survey by vice versa. a ship at full speed. Eggs of the target species a ship at full speed. Eggs of the target species are identified live at sea, for near-real-time Similar results have been obtained off northern are identified live at sea, for near-real-time Similar results have been obtained off northern mapping and adaptive sampling, and all eggs are Peru for eggs of the anchoveta (Engraulis mapping and adaptive sampling, and all eggs are Peru for eggs of the anchoveta (Engraulis identified and counted ashore in preserved ringens) and euphausiids. This is work in identified and counted ashore in preserved ringens) and euphausiids. This is work in samples. At sea, simultaneous measurement is progress in collaboration with Dra. Guadalupe samples. At sea, simultaneous measurement is progress in collaboration with Dra. Guadalupe made of date, time, location, temperature, Sanchez (Instituto del Mar del Peru). In essence, made of date, time, location, temperature, Sanchez (Instituto del Mar del Peru). In essence, salinity, and chlorophyll a fluorescence. anchoveta eggs and euphausiids, occurred but not salinity, and chlorophyll a fluorescence. anchoveta eggs and euphausiids, occurred but not Euphausiids and other plankters are collected as together. Euphausiids and other plankters are collected as together. “by-catch” of the egg sampling. “by-catch” of the egg sampling. The most parsimonious explanation of these The most parsimonious explanation of these Sardine and anchovy eggs sampled during patterns is euphausiid predation on sardine eggs. Sardine and anchovy eggs sampled during patterns is euphausiid predation on sardine eggs. CalCOFI cruise 9603JD were distributed in a These results and those of others indicated that CalCOFI cruise 9603JD were distributed in a These results and those of others indicated that complementary fashion. Sardine eggs were most variation in the abundance and distribution of complementary fashion. Sardine eggs were most variation in the abundance and distribution of
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