Fish Stock Development under Hydrographic and Hydrochemical Aspects, the History of Baltic Sea Fisheries and Its Management

Hammer, Cornelius; Dorrien, Christian von; Ernst, Peter; Gröhsler, Tomas; Köster, Fritz; MacKenzie, Brian R.; Möllmann, Christian; Wegner, Gerd; Zimmermann, Christopher

doi:10.1002/9780470283134.ch18

Cited by 13 publications

(24 citation statements)

References 59 publications

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“…The species composition of the flatfish community has changed over time during the past century. In the early decades of the 1900s, plaice ( Pleuronectes platessa ) and dab ( Limanda limanda ) were abundant in the Bornholm Basin, but they declined in the 1950s–1970s and are rare in this area at present [139], [143]. The relatively high abundance and widespread distribution of flounder in the Baltic, but low abundance of the plaice and dab, may be partly related to differences in salinity tolerance of eggs and in reproduction [144].…”

Section: Resultsmentioning

confidence: 99%

Status of Biodiversity in the Baltic Sea

et al. 2010

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The brackish Baltic Sea hosts species of various origins and environmental tolerances. These immigrated to the sea 10,000 to 15,000 years ago or have been introduced to the area over the relatively recent history of the system. The Baltic Sea has only one known endemic species. While information on some abiotic parameters extends back as long as five centuries and first quantitative snapshot data on biota (on exploited fish populations) originate generally from the same time, international coordination of research began in the early twentieth century. Continuous, annual Baltic Sea-wide long-term datasets on several organism groups (plankton, benthos, fish) are generally available since the mid-1950s. Based on a variety of available data sources (published papers, reports, grey literature, unpublished data), the Baltic Sea, incl. Kattegat, hosts altogether at least 6,065 species, including at least 1,700 phytoplankton, 442 phytobenthos, at least 1,199 zooplankton, at least 569 meiozoobenthos, 1,476 macrozoobenthos, at least 380 vertebrate parasites, about 200 fish, 3 seal, and 83 bird species. In general, but not in all organism groups, high sub-regional total species richness is associated with elevated salinity. Although in comparison with fully marine areas the Baltic Sea supports fewer species, several facets of the system's diversity remain underexplored to this day, such as micro-organisms, foraminiferans, meiobenthos and parasites. In the future, climate change and its interactions with multiple anthropogenic forcings are likely to have major impacts on the Baltic biodiversity.

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Section: Resultsmentioning

confidence: 99%

Status of Biodiversity in the Baltic Sea

et al. 2010

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“…The impact of fishing on the cod stock was first apparent during the Second World War when the intensive cod fishery in the Baltic Sea began (Meyer 1952, Eero et al 2008) and continued to develop during the 1950s-1960s. Thereafter, the exploitation rates gradually declined, although landings remained relatively stable (Hammer et al 2008). The decline in fishing mortality was first apparent for younger cod (Eero et al 2007), which was partly due to new technical measures (minimum landings size, mesh size) introduced to protect the stock (e.g., Kosior 1974).…”

Section: Fishingmentioning

confidence: 99%

“…The cod fishery intensified again in the 1980s (Hammer et al 2008), stimulated by the observed large increase in stock size and simultaneous decline in pelagic stocks (ICES 2009). The period of a large cod fishery, however, did not last long, as it coincided with the onset FIG.…”

Section: Fishingmentioning

confidence: 99%

“…The newly reconstructed time-series of cod stock dynamics extends to the period when the Baltic was still considered oligotrophic and contained large seal populations. Moreover, due to relatively late developments in fishing technology compared to other areas in the North Atlantic, exploitation of cod in the Baltic was low until the 1940s-1950s (Eero et al 2008, Hammer et al 2008). This combination of long ecological data sets transcending the historical development of key human impacts is relatively rare in marine ecology, and enables us to investigate in a chronological and process-oriented fashion how the onset of those impacts affected the population dynamics and productivity of a large piscivorous predator species.…”

Section: Introductionmentioning

confidence: 99%

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Multi-decadal responses of a cod (Gadus morhua) population to human-induced trophic changes, fishing, and climate

Eero

MacKenzie

Köster

et al. 2011

Ecological Applications

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Understanding how human impacts have interacted with natural variability to affect populations and ecosystems is required for sustainable management and conservation. The Baltic Sea is one of the few large marine ecosystems worldwide where the relative contribution of several key forcings to changes in fish populations can be analyzed with empirical data. In this study we investigate how climate variability and multiple human impacts (fishing, marine mammal hunting, eutrophication) have affected multi-decadal scale dynamics of cod in the Baltic Sea during the 20th century. We document significant climate-driven variations in cod recruitment production at multi-annual timescales, which had major impacts on population dynamics and the yields to commercial fisheries. We also quantify the roles of marine mammal predation, eutrophication, and exploitation on the development of the cod population using simulation analyses, and show how the intensity of these forcings differed over time. In the early decades of the 20th century, marine mammal predation and nutrient availability were the main limiting factors; exploitation of cod was still relatively low. During the 1940s and subsequent decades, exploitation increased and became a dominant forcing on the population. Eutrophication had a relatively minor positive influence on cod biomass until the 1980s. The largest increase in cod biomass occurred during the late 1970s, following a long period of hydrographically related above-average cod productivity coupled to a temporary reduction in fishing pressure. The Baltic cod example demonstrates how combinations of different forcings can have synergistic effects and consequently dramatic impacts on population dynamics. Our results highlight the potential and limitations of human manipulations to influence predator species and show that sustainable management can only be achieved by considering both anthropogenic and naturally varying processes in a common framework.

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“…A dramatic reduction in the cod stock and profit in the late 1980s resulted in increased industrial fisheries for sprat and herring (ICES, 2010). TACs for sprat and herring in the Baltic Sea were introduced in 1977, but were initially relatively high in relation to the catches and did not limit the fishery until the late 1990s (Hammer et al, 2001). While the Baltic pelagic mixed fishery is fairly simple in terms of species richness and has a reasonable data collection, the Baltic Sea fisheries assessment Working Group of ICES (WGBFAS) has since 2004 reported that misreporting of species composition exists in this fishery and is considered to negatively affect certainty in the stock assessment (e.g.…”

Section: Introductionmentioning

confidence: 99%

Does fisheries management incentivize non-compliance? Estimated misreporting in the Swedish Baltic Sea pelagic fishery based on commercial fishing effort

Hentati‐Sundberg

Hjelm

Österblom

2014

ICES Journal of Marine Science

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Hentati-Sundberg, J., Hjelm, J., and Ö sterblom, H. Does fisheries management incentivize non-compliance? Estimated misreporting in the Swedish Baltic Sea pelagic fishery based on commercial fishing effort. -ICES Journal of Marine Science, 71: 1846 -1853. Fisheries management agencies and fishing industry representatives depend on reliable estimates of fish biomass and mortality for the determination of sustainable catch levels. Lack of data or misreporting may be reasons for unreliable stock assessment, which, in turn, may result in advice that does not reflect the availability of fisheries resources. It has been suggested that the mixed pelagic trawl fisheries in the Baltic represent a case of biased estimates of fish biomass and mortality resulting from misreporting. Here, we estimate the degree of misreporting in the Swedish pelagic fishery (1996 -2009) and propose an approach for reconstructing historical catches based on commercial effort data. The analysis suggests that total catches have been underestimated during part of our study period and that systematic misreporting of species composition has taken place over the whole study period. The analysis also suggests that there is overcapacity in the fishery and that such economic incentive could explain the general patterns of misreporting. Applying our method for fisheries with suspected misreporting could significantly improve assessment accuracy, reduce uncertainty and thereby allow for a better link between catches and resource levels.

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Fish Stock Development under Hydrographic and Hydrochemical Aspects, the History of Baltic Sea Fisheries and Its Management

Cited by 13 publications

References 59 publications

Status of Biodiversity in the Baltic Sea

Status of Biodiversity in the Baltic Sea

Multi-decadal responses of a cod (Gadus morhua) population to human-induced trophic changes, fishing, and climate

Does fisheries management incentivize non-compliance? Estimated misreporting in the Swedish Baltic Sea pelagic fishery based on commercial fishing effort

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