Award: OCE-1158683

Award Title: Collaborative Proposal: CAMEO: Using interdecadal comparisons to understand trade-offs between abundance and condition in fishery ecosystems
Funding Source: NSF Division of Ocean Sciences (NSF OCE)
Program Manager: David L. Garrison

Outcomes Report

Oceans are a primary source of protein for people around the world. This fact makes rising ocean temperatures of particular concern as they are expected to significantly alter marine ecosystems and food webs by increasing metabolic rates, altering primary production, pushing the physiological limits of some species, and shifting distributions of other species. Pelagic forage fishes play critical roles in marine food webs by linking production from lower trophic levels (zooplankton) to higher trophic levels (larger piscivores such as tuna, striped bass, and marine mammals) and moving energy from feeding grounds to other ecosystems. The amount of energy moved across trophic levels or to new systems is directly linked to forage fish consumption rate. To better understand how climate change, commercial fishing, or other human impacts might affect marine systems, baseline estimates of forage fish consumption are needed. In the Gulf of Maine, Atlantic herring play pivotal ecological and economic roles by supporting the ecosystem and valuable commercial fisheries. In this study, we estimated the consumption rate of Atlantic herring in the Gulf of Maine to provide a baseline estimate for how this forage fish may transfer energy through the system. We first used a mercury-mass balance model to estimate annual consumption by herring, based on a diet equivalent to the calanoid copepod Calanus. Our estimates ranged from 51,408,900 MT in 2001 when the herring population was high to 7,064,800 MT in 2010 when the herring population was low. Interestingly, our modeling indicated herring consumption, when standardized to body size, increased with age, suggesting herring shift their diets or activity dramatically as they grow. Both hypotheses were supported when evaluated with an alternative model, but life history characteristics of herring suggest increased activity (i.e., migration) as herring grow is a more likely explanation for increased consumption (and energy demand) with size. Our results suggest highly-migratory fish species may have unique physiological requirements as they grow, and these should be considered when estimating prey consumption or energy demand of these species. This work supported the training of a MasterÆs of Science graduate student in quantitative modeling. Last Modified: 10/24/2014 Submitted by: Jason Stockwell

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Principal Investigator: Jason Stockwell (University of Vermont & State Agricultural College)