Geology Reports⌕ Search
Home/Archive/USGS

USGS · 70024473

Comparison of stomach contents of haddock (Melanogrammus aeglefinus) from the 1981 and 1991 North Sea International Stomach Sampling Projects

S.A. Adlerstein·A. Temming·N. Mergardt
View original source ↗Export metadata ↓

Abstract

This study analyses data from over 20 000 haddock stomachs collected during the 1981 and 1991 Stomach Sampling Projects of the North Sea. Sampling was within the framework of the Multispecies Virtual Population Analysis (MSVPA) for fisheries stock assessment. In 1981 stomachs were collected to calculate input feeding parameters from main predators. During 1991 the sampling exercise was repeated to test stability of the parameters in the region. We investigate stability of haddock stomach content weight between years accounting for ontogenic, spatial and temporal variations within the scope of the survey resolution. Analysis using generalized linear and additive models is performed for weight of the stomach content including and excluding empty stomachs and also for proportion of stomachs without food. Results indicate that haddock stomach contents varied significantly between years, quarters and North Sea roundfish areas. Content weights were overall higher in 1981 than in 1991. In 1981 levels were high from spring to fall and in 1991 mostly in spring. During both years levels were lowest in the central North Sea and in winter. Most of the deviance in modelling the stomach weight is explained by the length of the predator. Stomachs sampled in 1981 were most frequently empty in spring and those sampled in 1991 in winter. In both years, proportions decreased with fish length except in winter when levels increased. Proportion of empty stomachs was highest in the central region of the North Sea. Most of the proportion variation is explained by quarterly fluctuation. Variation of content weight can be related to prey composition found in the stomachs. High stomach contents are generally associated with high contribution of fish prey to the total stomach content, mainly sandeels. We propose that sandeels were more vulnerable to predation in 1981 than in 1991 due to colder temperatures. ?? 2002 International Council for the Exploration of the Sea. Published by Elsevier Science Ltd.

Explore related subjects

ICES Journal of Marine ScienceArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

S.A. Adlerstein, A. Temming, N. Mergardt. 2002. Comparison of stomach contents of haddock (Melanogrammus aeglefinus) from the 1981 and 1991 North Sea International Stomach Sampling Projects. https://doi.org/10.1006/jmsc.2002.1197

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2025

Integrating marine historical ecology into management of Alaska’s Pacific cod fishery for climate readiness

The Pacific cod ( Gadus macrocephalus ) fishery was closed in 2020 after a rapid decline in biomass caused by the marine heat waves of 2014–2019. Pacific cod are exceptionally thermally sensitive and management of this fishery is now challenged by increasingly unpredictable climate conditions. Fisheries monitoring is critical for climate readiness, but short-term monitoring data may be inadequate for recognizing and anticipating change under rapid climate changes. We propose an interdisciplinary, marine historical ecology framework that looks to long-term records (local and traditional knowledge, history, archaeology, and paleoclimatology) to capture a long range of ecological variability and provide historical context for management. In order to connect to contemporary fisheries management, this framework must be built on a common vocabulary and an understanding of the key metrics used in fisheries stock assessments. Here, we propose metrics derived from Pacific cod stock assessment and synthesize information relevant to understanding the effects of past warming periods on cod populations across the Gulf of Alaska and Bering Sea. This case study provides a framework for thinking about how to use these historical records in the context of fisheries management under rapidly changing climate conditions.

Alaska↗
USGS2024

Reconstructing half a century of coregonine recruitment reveals species-specific dynamics and synchrony across the Laurentian Great Lakes

Understanding how multiple species and populations vary in their recruitment dynamics can elucidate the processes driving recruitment across space and time. Lake Whitefish ( Coregonus clupeaformis ) and Cisco ( C. artedi ) are socioecologically important fishes across their range; however, many Laurentian Great Lakes populations have experienced declining, poor, or sporadic recruitment in recent decades. We integrated catch and age data from 38 long-term surveys across each of the Great Lakes and Lake Simcoe, resulting in a combined time series spanning 1960–2019. We estimated Lake Whitefish and Cisco year-class strength (YCS) in each lake using longitudinal mixed-effects regressions of relative cohort abundance. We subsequently quantified interspecific, spatial, and temporal synchrony in YCS using correlation and dynamic factor analyses. Lake Whitefish YCS was positively spatially synchronous on average, and YCS in all six lakes was elevated during the 1980s–1990s. In contrast, Cisco YCS was sporadic, not spatially synchronous, and highly variable around long-term, lake-specific means. YCS was not synchronous between species in any lake. Collectively, our analyses demonstrate that these species exhibit differential recruitment dynamics that may be regulated by species-specific factors. Results from this study can be leveraged in future research on the causes and consequences of cross-species, cross-basin recruitment variability.

Laurentian Great Lakes↗
USGS2023

Temporal, environmental, and demographic correlates of Ichthyophonus sp. infections in mature Pacific herring populations

Causes of population collapse and failed recovery often remain enigmatic in marine forage fish like Pacific herring ( Clupea pallasii ) that experience dramatic population oscillations. Diseases such as ichthyophoniasis are hypothesized to contribute to these declines, but lack of long-term datasets frequently prevents inference. Analysis of pathogen surveillance and population assessment datasets spanning 2007–2019 indicate that the age-based prevalence estimate of Ichthyophonus infection was, on average, 54% greater among a collapsed population of Pacific herring (Prince William Sound, Alaska, USA) as compared to a nearby population (Sitka Sound, Alaska, USA) that is relatively robust. During the study years, the age-based infection prevalence ranged from 14 to 44% in Prince William Sound and 5 to 33% in Sitka Sound. At both sites, the age-based infection prevalence declined over time, with an average decrease of 7% per year. Statistical analyses indicated that infection prevalence between the two populations was reduced by regional factors affecting both sites, and that these factors were independent of herring density. Infection prevalence in both populations was positively correlated with herring age and negatively correlated with the Pacific Decadal Oscillation. This study demonstrates how synthesis of environmental, stock assessment, and disease assessment data can be leveraged to elucidate epidemiological trends in diseases of wild fish.

ICES Journal of Marine Science↗