Comparing demersal fish assemblages between periods of contrasting climate and fishing pressure

Abstract ter Hofstede, R., and Rijnsdorp, A. D. 2011. Comparing demersal fish assemblages between periods of contrasting climate and fishing pressure. – ICES Journal of Marine Science, 68: 1189–1198. Fish communities are dynamic and their structure is known to change over time. Traditionally, these changes were considered to be fisheries-induced, but recent analyses also suggest that global warming could affect the distribution, abundance, and assemblage composition of marine fish. However, disentangling the effects of fisheries and those resulting from climate change is difficult, because both potential drivers act simultaneously. In our study, we distinguished between the effects of fisheries and climate change on the fish assemblage of the southern North Sea by comparing survey catch data for that region during four unique periods throughout the past century, characterized by (i) low fishing pressure during a cold period (1902–1908), (ii) low fishing pressure during a warm period (1950–1956), (iii) high fishing pressure during a cold period (1978–1984), and (iv) high fishing pressure during a warm period (2002–2008). Our analysis indicates that the demersal fish community in the southern North Sea has changed in response to changes in both climate and fishing pressure. Our results suggest both a relatively higher richness of Lusitanian (warm-favouring) species compared with boreal (cool-favouring) species, and a lower mean body size of the fish community during times of warming, independent of fishing pressure.

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The response of the North Sea demersal fish community to changing fishing pressure as seen through the prism of the large fish indicator

Fisheries Research ◽

10.1016/j.fishres.2016.05.002 ◽

2016 ◽

Vol 181 ◽

pp. 222-233 ◽

Cited By ~ 1

Author(s):

Antonios Stamoulis ◽

Els Torreele

Keyword(s):

North Sea ◽

Fish Community ◽

Demersal Fish ◽

Fishing Pressure ◽

Large Fish ◽

The North ◽

The North Sea

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Dissolved oxygen and temperature best predict deep-sea fish community structure in the Gulf of California with climate change implications

Marine Ecology Progress Series ◽

10.3354/meps13240 ◽

2020 ◽

Vol 637 ◽

pp. 159-180

Author(s):

ND Gallo ◽

M Beckwith ◽

CL Wei ◽

LA Levin ◽

L Kuhnz ◽

...

Keyword(s):

Climate Change ◽

Community Structure ◽

Community Composition ◽

Environmental Conditions ◽

Deep Sea ◽

Gulf Of California ◽

Fish Community ◽

Demersal Fish ◽

Fish Community Structure ◽

Explained Variance

Natural gradient systems can be used to examine the vulnerability of deep-sea communities to climate change. The Gulf of California presents an ideal system for examining relationships between faunal patterns and environmental conditions of deep-sea communities because deep-sea conditions change from warm and oxygen-rich in the north to cold and severely hypoxic in the south. The Monterey Bay Aquarium Research Institute (MBARI) remotely operated vehicle (ROV) ‘Doc Ricketts’ was used to conduct seafloor video transects at depths of ~200-1400 m in the northern, central, and southern Gulf. The community composition, density, and diversity of demersal fish assemblages were compared to environmental conditions. We tested the hypothesis that climate-relevant variables (temperature, oxygen, and primary production) have more explanatory power than static variables (latitude, depth, and benthic substrate) in explaining variation in fish community structure. Temperature best explained variance in density, while oxygen best explained variance in diversity and community composition. Both density and diversity declined with decreasing oxygen, but diversity declined at a higher oxygen threshold (~7 µmol kg-1). Remarkably, high-density fish communities were observed living under suboxic conditions (<5 µmol kg-1). Using an Earth systems global climate model forced under an RCP8.5 scenario, we found that by 2081-2100, the entire Gulf of California seafloor is expected to experience a mean temperature increase of 1.08 ± 1.07°C and modest deoxygenation. The projected changes in temperature and oxygen are expected to be accompanied by reduced diversity and related changes in deep-sea demersal fish communities.

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Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community

ICES Journal of Marine Science ◽

10.1093/icesjms/fsr188 ◽

2012 ◽

Vol 69 (1) ◽

pp. 8-22 ◽

Cited By ~ 18

Author(s):

Simon P. R. Greenstreet ◽

Helen M. Fraser ◽

Stuart I. Rogers ◽

Verena M. Trenkel ◽

Stephen D. Simpson ◽

...

Keyword(s):

North Sea ◽

Fish Community ◽

Size Structure ◽

Demersal Fish ◽

Community Size ◽

The North ◽

Management Objectives ◽

The North Sea ◽

Composition Structure ◽

And Function

Abstract Greenstreet, S. P. R., Fraser, H. M., Rogers, S. I., Trenkel, V. M., Simpson, S. D., and Pinnegar, J. K. 2012. Redundancy in metrics describing the composition, structure, and functioning of the North Sea demersal fish community. – ICES Journal of Marine Science, 69: 8–22. Broader ecosystem management objectives for North Sea demersal fish currently focus on restoring community size structure. However, most policy drivers explicitly concentrate on restoring and conserving biodiversity, and it has not yet been established that simply restoring demersal fish size composition will be sufficient to reverse declines in biodiversity and ensure a generally healthy community. If different aspects of community composition, structure, and function vary independently, then to monitor all aspects of community general health will require application of a suite of metrics. This assumes low redundancy among the metrics used in any such suite and implies that addressing biodiversity issues specifically will require explicit management objectives for particular biodiversity metrics. This issue of metric redundancy is addressed, and 15 metrics covering five main attributes of community composition, structure, and function are applied to groundfish survey data. Factor analysis suggested a new interpretation of the metric information and indicated that a minimum suite of seven metrics was necessary to ensure that all changes in the general health of the North Sea demersal fish community were monitored properly. Covariance among size-based and species-diversity metrics was low, implying that restoration of community size structure would not necessarily reverse declines in species diversity.

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