scholarly journals Do climate and fishing influence size-based indicators of Celtic Sea fish community structure?

2005 ◽  
Vol 62 (3) ◽  
pp. 405-411 ◽  
Author(s):  
Julia L. Blanchard ◽  
Nicholas K. Dulvy ◽  
Simon Jennings ◽  
James R. Ellis ◽  
John K. Pinnegar ◽  
...  
Keyword(s):  
Community Structure ◽  
Size Structure ◽  
Anthropogenic Impacts ◽  
Fishing Effort ◽  
Limited Area ◽  
Fish Community Structure ◽  
Community Metrics ◽  
Celtic Sea ◽  
Using Data ◽  
Sea Fish

Abstract Ecosystem-based management requires the development of indicators that allow anthropogenic impacts to be detected against the background of natural variation. Size-based community metrics are potentially useful indicators because of their theoretical foundation and practical utility. Temporal and spatial patterns in size-based community metrics for Celtic Sea fish are described and calculated using data from the English groundfish survey of the area (1987–2003). The results reveal that the size structure of the community has changed over time, and that a decrease in the relative abundance of larger fish was accompanied by an increase in smaller fish (4–25 g). Temporal analyses of the effects of fishing and climate variation suggest that fishing generally has had a stronger effect on size structure than changes in temperature. Therefore, size-based metrics respond clearly to the effects of fishing even in variable environments, reflecting the ubiquity of size-based processes in defining community structure and responses to mortality. Spatial analyses were inconclusive, probably owing to the limited area for which fishing effort, temperature, and survey data were all available.

scholarly journals Fishing and environment drive spatial heterogeneity in Celtic Sea fish community size structure

2011 ◽  
Vol 68 (10) ◽  
pp. 2106-2113 ◽  
Author(s):  
Samuel Shephard ◽  
Hans D. Gerritsen ◽  
Michel J. Kaiser ◽  
Holly S. Truszkowska ◽  
David G. Reid
Keyword(s):  
Spatial Heterogeneity ◽  
Fish Community ◽  
Size Structure ◽  
Fishing Effort ◽  
Trawl Survey ◽  
Weak Effect ◽  
Community Size ◽  
Negative Effect ◽  
Celtic Sea ◽  
Sea Fish

Abstract Shephard, S., Gerritsen, H. D., Kaiser, M. J., Truszkowska, H. S., and Reid, D. G. 2011. Fishing and environment drive spatial heterogeneity in Celtic Sea fish community size structure. – ICES Journal of Marine Science, 68: 2106–2113. The Large Fish Indicator (LFI) is a univariate size-based indicator of fish community state that has been selected to support the OSPAR fish community Ecological Quality Objective (EcoQO). To operate this EcoQO, a survey-based LFI for each OSPAR region needs to be developed. However, fish communities in these regions are spatially heterogeneous, and there is evidence of within-region spatial variation in the LFI that could confound an overall indicator series. For Celtic Sea trawl-survey sites, spline correlograms indicate positive spatial autocorrelation at a similar range (∼40 km) for the LFI and for fishing effort (h year−1) from vessel monitoring systems. Statistical models reveal a strong negative effect on annual LFI by site of fishing effort within a radius of 40 km. There was a weak effect of fishing within 20 km and no effect at 10 km. LFI also varied significantly with substratum and with local fish community composition identified by a resemblance matrix derived from the survey data. Finally, there was a weak effect of survey year on LFI. Spatial stratification of LFI calculations may be necessary when developing size-based indicators for OSPAR or Marine Strategy Framework Directive regions.

scholarly journals Size-selective fishing drives species composition in the Celtic Sea

2012 ◽  
Vol 69 (2) ◽  
pp. 223-234 ◽  
Author(s):  
Samuel Shephard ◽  
Tak Fung ◽  
Jennifer E. Houle ◽  
Keith D. Farnsworth ◽  
David G. Reid ◽  
...  
Keyword(s):  
Species Composition ◽  
Relative Abundance ◽  
Size Structure ◽  
Large Species ◽  
Strongly Correlated ◽  
Large Fish ◽  
Fish Community Structure ◽  
Community Size ◽  
Two Indices ◽  
Celtic Sea

Abstract Shephard, S., Fung, T., Houle, J. E., Farnsworth, K. D., Reid, D. G., and Rossberg, A. G. 2012. Size-selective fishing drives species composition in the Celtic Sea. – ICES Journal of Marine Science, 69: 223–234. Fishing alters community size structure by selectively removing larger individual fish and by changing the relative abundance of different-sized species. To assess the relative importance of individual- and species-level effects, two indices of fish community structure were compared, the relative abundance of large fish individuals (large fish indicator, LFI) and the relative abundance of large fish species (large species indicator, LSI). The two indices were strongly correlated for empirical data from the Celtic Sea and for data from simulated model communities, suggesting that much of the variability in the LFI is caused by shifts in the relative abundance of species (LSI). This correlation is explained by the observation that most of the biomass of a given species is spread over few length classes, a range spanning the factor 2 of individual length, such that most species contributed predominantly to either the small or the large component of the LFI. The results suggest that the effects of size-selective fishing in the Celtic Sea are mediated mainly through changes in community composition.

Relating groundfish diversity and biomass to deepsea corals and sponges using trawl survey catch data

2020 ◽  
Vol 646 ◽  
pp. 127-143
Author(s):  
KL Bosley ◽  
KM Bosley ◽  
AA Keller ◽  
CE Whitmire
Keyword(s):  
Community Structure ◽  
Fish Habitat ◽  
Environmental Parameters ◽  
Demersal Fish ◽  
Trawl Survey ◽  
Fish Community Structure ◽  
Bottom Temperature ◽  
Fisheries Science ◽  
Using Data ◽  
Species Specific

Deep-sea corals and sponges (DSCS) inhabit the world’s oceans and are often associated with high fish abundance. However, the precise nature and extent of any association is difficult to quantify and remains poorly understood. We investigated associations between DSCS and demersal fish using data from the Northwest Fisheries Science Center’s bottom trawl survey (2003-2015). General linear mixed models showed that average species density of groundfish was slightly higher and groundfish biomass slightly lower in tows with DSCS. Multivariate analyses were used to examine relationships among fish community structure, DSCS biomass, and environmental parameters (depth, latitude, bottom temperature). No strong correlations occurred between the community structure of groundfish and DSCS biomass; instead, bottom temperature and depth were the primary drivers of community composition. However, indicator species analysis also showed various species-specific associations with DSCS. Specifically, some flatfish species exhibited relationships with coral and sea pen biomass, whereas some rockfishes were associated with high sponge biomass. Our results provide information on the broad-scale associations among DSCS and demersal fishes that may be useful for developing studies focused on the functional value of DSCS as essential fish habitat and the role they play in groundfish life history and ecology.

scholarly journals Testing candidate indicators to support ecosystem-based management: the power of monitoring surveys to detect temporal trends in fish community metrics

2004 ◽  
Vol 61 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Mike D Nicholson ◽  
Simon Jennings
Keyword(s):  
Community Structure ◽  
Time Scales ◽  
Fish Community ◽  
Temporal Trends ◽  
Fish Stock ◽  
Trawl Survey ◽  
Fish Community Structure ◽  
Ecosystem Based Management ◽  
Community Metrics ◽  
Fish Community Metrics

Abstract Community metrics describe aspects of community structure and are often calculated from species-size-abundance data collected during fish stock monitoring surveys. Several community metrics have been proposed as indicators to support ecosystem-based fishery management. These metrics should be sensitive to fishing impacts and respond rapidly to management action, so that managers can assess whether changes in the fish community are a desirable or undesirable response to management. It should also be possible to estimate metrics with sufficient precision so that changes in the community can be detected on management time scales of a year to a few years. Here, we test the power of a large-scale annual trawl survey (North Sea International Bottom Trawl Survey, IBTS) to detect trends in six community metrics: mean length, mean weight, mean maximum length, mean maximum weight, slope of the biomass size spectrum, and mean trophic level. Our analyses show that the power of the trawl survey to detect trends is generally poor. While community metrics do provide good long-term indicators of changes in fish community structure, they are unlikely to provide an appropriate tool to support short-term management decisions. If fish community metrics are to provide effective support for ecosystem-based management, and management time scales cannot be extended, then the power of many surveys to detect trends in fish community structure will need to be improved by increased replication and standardization.

Size Structure of a Lake Trout (Salvelinus namaycush) Population an Arctic Lake: Influence of Angling and Implications for Fish Community Structure

1989 ◽  
Vol 46 (12) ◽  
pp. 2153-2156 ◽  
Author(s):  
Michael E. McDonald ◽  
Anne E. Hershey
Keyword(s):  
Community Structure ◽  
Fish Community ◽  
Lake Trout ◽  
Size Structure ◽  
Salvelinus Namaycush ◽  
Fish Community Structure ◽  
Median Length ◽  
Arctic Alaska ◽  
Gill Net ◽  
Toolik Lake

The lake trout (Salvelinus namaycush) population in Toolik Lake in arctic Alaska was assessed by gill net during 1977, prior to exploitation. In 1986 we replicated the gill net study to determine the effects of recent angling pressure on the fish community. Relative composition of the catch varied between samples. Round whitefish (Prosopium cylindraceum), which are not susceptible to angling, made up 42% of the catch in 1986 and 28% in 1977. Significant reductions in the median length and weight of lake trout between the sampling periods were observed. The median size of lake trout in 1986 was below the minimum 1977 reproductive size. Differences in median length and weight of grayling (Thymallus arcticus) and of round whitefish during this period were not significantly different. The condition factor of lake trout was significantly higher in 1986. We suggest that large lake trout in Toolik Lake control salmonid recruitment and determine community structure. With continued fishing pressure further changes in the fish community and lake trophic dynamics may result.

Fish community structure, habitat complexity, and soundscape characteristics of patch reefs in a tropical, back-reef system

2019 ◽  
Vol 609 ◽  
pp. 33-48 ◽  
Author(s):  
RP Lyon ◽  
DB Eggleston ◽  
DR Bohnenstiehl ◽  
CA Layman ◽  
SW Ricci ◽  
...  
Keyword(s):  
Community Structure ◽  
Habitat Complexity ◽  
Fish Community ◽  
Back Reef ◽  
Fish Community Structure ◽  
Patch Reefs ◽  
Reef System

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

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.

Keystone species of fish community structure in the Bohai Sea

2018 ◽  
Vol 25 (2) ◽  
pp. 229
Author(s):  
Zhongyi LI ◽  
Qiang WU ◽  
Xiujuan SHAN ◽  
Tao YANG ◽  
Fangqun DAI ◽  
...  
Keyword(s):  
Community Structure ◽  
Fish Community ◽  
Bohai Sea ◽  
Keystone Species ◽  
Fish Community Structure ◽  
The Bohai Sea

Preliminary observations on abundance and distribution of fish fauna in a canyon of the Bay of Biscay (ICES Division 8c)

2021 ◽  
pp. 1-10
Author(s):  
G. Diez ◽  
L. Arregi ◽  
M. Basterretxea ◽  
E. Cuende ◽  
I. Oyarzabal
Keyword(s):  
Deep Sea ◽  
Basque Country ◽  
Fish Fauna ◽  
Fishing Effort ◽  
Fishing Gear ◽  
Clear Trend ◽  
Depth Ranges ◽  
Abundance And Distribution ◽  
Sea Fish ◽  
Distribution Of Fish

Abstract The changes in abundance and biodiversity of deep-sea fish fauna are described based on an annual deep-water longline survey with data collected during the period 2015–2019 in the Basque Country continental Slope (ICES Division 8c). The sampling scheme included hauls in four 400 m strata, from 650–2250 m deep. The DST sensors installed in the main line have allowed us to set an accurate soak time for each haul, and they were used to calculate fishing effort and CPUE by haul. The catchability of the fishing gear indicated that 15% of the total hooks deployed in the five-year period were able to fish, and that the bottom longline was very effective in fishing a wide number of different species in all depth ranges. The fishing gear caught 14 different species of sharks (13 deepwater and one pelagic), two chimaeras and nine teleosts. The abundance and biomass registered on the hooks attached to the bottom were between three and four times higher than in the floating sections, and the highest CPUE and biomass were recorded between 1051–1450 m, from 2015 to 2017, and in the 1451–1850 m strata, but they do not show any clear trend throughout the five years of the series.

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