Type of Presentation

Poster

Session Title

Ecological and cultural context of Pacific herring in the Salish Sea

Description

The feeding ecology of herring, surf smelt, and northern anchovy in the Strait of Georgia were investigated to determine dietary overlap and potential competition for food resources. Samples were collected using a small midwater trawl during September 2014, near and south of the Fraser River Mouth onboard the CCGS Neocaligus. The stomach contents of a total of 113 fish were identified and enumerated, including 57 Pacific herring (standard length (SL): 105-168 mm), 36 surf smelt (SL: 119-166 mm), and 20 northern anchovy (SL: 53-74 mm), and quantitatively analyzed to determine within and between species diet similarities. All fish were actively feeding. Hierarchical cluster analysis of the diets revealed distinct feeding niches for each of these three zooplankton consumers. Herring had the most diverse diet, consisting mainly (93% of the prey mass) of copepods (Calanus pacificus, Epilabidocera amphitrites and C. marshallae), hyperiids (Themisto and Hyperoche) and decapods (brachiurian and caridean zoaea). Anchovies preyed on a mix of gelatinous plankton, euphausiids (Thysanoessa), amphipods, small copepods (Corycaeus, Tigropus, Oncaea, Acartia), as well as barnacle and gastropod larvae. Smelts appeared to be specialist jellyfish consumers (~90% by mass) with occasional ingestion of amphipods, small copepods and fish larvae. The forage fish analyzed here were sampled at the same location, yet showed little overlap in trophic niche. Prey similarity indices were < 25% between herring, smelts and anchovies and only reached ~40% between smelts and anchovies. Our preliminary data show a clear prey resource partitioning between sympatric forage fish suggesting potentially strong competition.

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Comparative feeding ecology of Pacific herring (Clupea pallasii), surf smelt (Hypomesus pretiosus), and northern anchovy (Engraulis mordax) in the Strait of Georgia, British Columbia, in fall 2014

2016SSEC

The feeding ecology of herring, surf smelt, and northern anchovy in the Strait of Georgia were investigated to determine dietary overlap and potential competition for food resources. Samples were collected using a small midwater trawl during September 2014, near and south of the Fraser River Mouth onboard the CCGS Neocaligus. The stomach contents of a total of 113 fish were identified and enumerated, including 57 Pacific herring (standard length (SL): 105-168 mm), 36 surf smelt (SL: 119-166 mm), and 20 northern anchovy (SL: 53-74 mm), and quantitatively analyzed to determine within and between species diet similarities. All fish were actively feeding. Hierarchical cluster analysis of the diets revealed distinct feeding niches for each of these three zooplankton consumers. Herring had the most diverse diet, consisting mainly (93% of the prey mass) of copepods (Calanus pacificus, Epilabidocera amphitrites and C. marshallae), hyperiids (Themisto and Hyperoche) and decapods (brachiurian and caridean zoaea). Anchovies preyed on a mix of gelatinous plankton, euphausiids (Thysanoessa), amphipods, small copepods (Corycaeus, Tigropus, Oncaea, Acartia), as well as barnacle and gastropod larvae. Smelts appeared to be specialist jellyfish consumers (~90% by mass) with occasional ingestion of amphipods, small copepods and fish larvae. The forage fish analyzed here were sampled at the same location, yet showed little overlap in trophic niche. Prey similarity indices were < 25% between herring, smelts and anchovies and only reached ~40% between smelts and anchovies. Our preliminary data show a clear prey resource partitioning between sympatric forage fish suggesting potentially strong competition.