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Assessing bottom trawling impacts based on the longevity of benthic invertebrates
Hiddink, Jan Geert ; Jennings, Simon ; Sciberras, Marija ; Bolam, Stefan G. ; Cambiè, Giulia ; McConnaughey, Robert A. ; Mazor, Tessa ; Hilborn, Ray ; Collie, Jeremy S. ; Pitcher, C.R. ; Parma, Ana M. ; Suuronen, Petri ; Kaiser, Michel J. ; Rijnsdorp, Adriaan D. - \ 2019
Journal of Applied Ecology 56 (2019)5. - ISSN 0021-8901 - p. 1075 - 1084.
benthic invertebrates - bottom trawl - fisheries management - impact assessment - life-history meta-analysis - seabed disturbance - systematic review
Bottom trawling is the most widespread human activity directly affecting seabed habitats. Assessment and effective management of the effects of bottom trawling at the scale of fisheries requires an understanding of differences in sensitivity of biota to trawling. Responses to disturbance are expected to depend on the intrinsic rate of increase in populations (r), which is expected to be linearly related to the reciprocal of longevity. We examine the relationship between the longevity of benthic invertebrates and their response to bottom trawling; both in terms of the immediate mortality following a trawl pass and their subsequent rates of recovery. We collate all available data from experimental and comparative trawling studies, and test how longevity influences these aspects of sensitivity. The shortest lived organisms (<1 year) increased in abundance shortly after experimental trawling but showed no response to trawling in long-term comparative studies. Conversely, the abundance of biota with a life span >1 year decreased by ~9% immediately following a trawl pass. The effect of bottom trawling in comparative studies increased with longevity, with a 2–3× larger effect on biota living >10 years than on biota living 1–3 years. We attribute this difference to the slower recovery rates of the long-lived biota. The observed relationship between the intrinsic rate of population increase (r, our metric of recovery rate) and the reciprocal of longevity matches theoretical expectation and predicts that the sensitivity of habitats to bottom trawling is higher in habitats with higher proportions of long-lived organisms. Synthesis and applications. Where the longevity of a species or the longevity distribution of a community is known or can be inferred, our estimates of depletion and intrinsic rate of increase can be combined with high-resolution maps of trawling intensity to assess trawling impacts at the scale of the fishery or other defined unit of assessment. Our estimates of r may also be used to estimate recovery times following other forms of seabed disturbance.
Data from: Assessing bottom-trawling impacts based on the longevity of benthic invertebrates
Hiddink, Jan Geert ; Jennings, Simon ; Sciberras, Marija ; Bolam, Stefan G. ; Cambiè, Giulia ; Mcconnaughey, Robert A. ; Mazor, Tessa ; Hilborn, Ray ; Collie, Jeremy S. ; Pitcher, C.R. ; Parma, Ana M. ; Suuronen, Petri ; Kaiser, Michel J. ; Rijnsdorp, A.D. - \ 2018
fisheries management - bottom trawl - benthic invertebrates - impact assessment - meta-analysis - systematic review - life history - seabed disturbance
Bottom trawling is the most widespread human activity directly affecting seabed habitats. Assessment and effective management of the effects of bottom trawling at the scale of fisheries requires an understanding of differences in sensitivity of biota to trawling. Responses to disturbance are expected to depend on the intrinsic rate of increase of populations (r), which is expected to be linearly related to the reciprocal of longevity. 2. We examine the relationship between the longevity of benthic invertebrates and their response to bottom trawling; both in terms of the immediate mortality following a trawl pass and their subsequent rates of recovery. We collate all available data from experimental and comparative trawling studies, and test how longevity influences these aspects of sensitivity. 3. The shortest-lived organisms (<1yr) increased in abundance shortly after experimental trawling, but showed no response to trawling in longer-term comparative studies. Conversely, the abundance of biota with a life-span >1yr decreased by ~9% immediately following a trawl pass. The effect of bottom trawling in comparative studies increased with longevity, with a 2-3× larger effect on biota living >10yr than on biota living 1-3yr. We attribute this difference to the slower recovery rates of the longer-lived biota. 4. The observed relationship between the intrinsic rate of population increase (r, our metric of recovery rate) and the reciprocal of longevity matches theoretical expectation and predicts that the sensitivity of habitats to bottom trawling is higher in habitats with higher proportions of long-lived organisms. 5. Synthesis and Applications. Where the longevity of a species or the longevity distribution of a community is known or can be inferred, our estimates of depletion and intrinsic rate of increase can be combined with high-resolution maps of trawling intensity to assess trawling impacts at the scale of the fishery or other defined unit of assessment. Our estimates of r may also be used to estimate recovery times following other forms of seabed disturbance.
Bottom trawl fishing footprints on the world’s continental shelves
Amoroso, Ricardo O. ; Pitcher, C.R. ; Rijnsdorp, Adriaan D. ; Mcconnaughey, Robert A. ; Parma, Ana M. ; Suuronen, Petri ; Eigaard, Ole R. ; Bastardie, Francois ; Hintzen, Niels T. ; Althaus, Franziska ; Baird, Susan Jane ; Black, Jenny ; Buhl-Mortensen, Lene ; Campbell, Alexander B. ; Catarino, Rui ; Collie, Jeremy ; Cowan, James H. ; Durholtz, Deon ; Engstrom, Nadia ; Fairweather, Tracey P. ; Fock, Heino O. ; Ford, Richard ; Gálvez, Patricio A. ; Gerritsen, Hans ; Góngora, María Eva ; González, Jessica A. ; Hiddink, Jan G. ; Hughes, Kathryn M. ; Intelmann, Steven S. ; Jenkins, Chris ; Jonsson, Patrik ; Kainge, Paulus ; Kangas, Mervi ; Kathena, Johannes N. ; Kavadas, Stefanos ; Leslie, Rob W. ; Lewis, Steve G. ; Lundy, Mathieu ; Makin, David ; Martin, Julie ; Mazor, Tessa ; Gonzalez-Mirelis, Genoveva ; Newman, Stephen J. ; Papadopoulou, Nadia ; Posen, Paulette E. ; Rochester, Wayne ; Russo, Tommaso ; Sala, Antonello ; Semmens, Jayson M. ; Silva, Cristina - \ 2018
Proceedings of the National Academy of Sciences of the United States of America 115 (2018)43. - ISSN 0027-8424 - p. E10275 - E10282.
Bottom trawlers land around 19 million tons of fish and invertebrates annually, almost one-quarter of wild marine landings. The extent of bottom trawling footprint (seabed area trawled at least once in a specified region and time period) is often contested but poorly described. We quantify footprints using high-resolution satellite vessel monitoring system (VMS) and logbook data on 24 continental shelves and slopes to 1,000-m depth over at least 2 years. Trawling footprint varied markedly among regions: from <10% of seabed area in Australian and New Zealand waters, the Aleutian Islands, East Bering Sea, South Overall, 14% of the 7.8 million-km2 study area was trawled, and 86% was not trawled. Trawling activity was aggregated; the most intensively trawled areas accounting for 90% of activity comprised 77% of footprint on average. Regional swept area ratio (SAR; ratio of total swept area trawled annually to total area of region, a metric of trawling intensity) and footprint area were related, providing an approach to estimate regional trawling footprints when highresolution spatial data are unavailable. If SAR was ≤0.1, as in 8 of 24 regions, therewas >95% probability that >90%of seabed was not trawled. If SAR was 7.9, equal to the highest SAR recorded, there was >95% probability that >70% of seabed was trawled. Footprints were smaller and SAR was ≤0.25 in regions where fishing rates consistently met international sustainability benchmarks for fish stocks, implying collateral environmental benefits from sustainable fishing.
Response of benthic fauna to experimental bottom fishing : A global meta-analysis
Sciberras, Marija ; Hiddink, Jan Geert ; Jennings, Simon ; Szostek, Claire L. ; Hughes, Kathryn M. ; Kneafsey, Brian ; Clarke, Leo J. ; Ellis, Nick ; Rijnsdorp, Adriaan D. ; Mcconnaughey, Robert A. ; Hilborn, Ray ; Collie, Jeremy S. ; Pitcher, C.R. ; Amoroso, Ricardo O. ; Parma, Ana M. ; Suuronen, Petri ; Kaiser, Michel J. - \ 2018
Fish and Fisheries 19 (2018)4. - ISSN 1467-2960 - p. 698 - 715.
Dredging - Effects of trawling - Fishing impacts - Invertebrate communities - Systematic review - Taxonomic analysis
Bottom-contact fishing gears are globally the most widespread anthropogenic sources of direct disturbance to the seabed and associated biota. Managing these fishing disturbances requires quantification of gear impacts on biota and the rate of recovery following disturbance. We undertook a systematic review and meta-analysis of 122 experiments on the effects-of-bottom fishing to quantify the removal of benthos in the path of the fishing gear and to estimate rates of recovery following disturbance. A gear pass reduced benthic invertebrate abundance by 26% and species richness by 19%. The effect was strongly gear-specific, with gears that penetrate deeper into the sediment having a significantly larger impact than those that penetrate less. Sediment composition (% mud and presence of biogenic habitat) and the history of fishing disturbance prior to an experimental fishing event were also important predictors of depletion, with communities in areas that were not previously fished, predominantly muddy or biogenic habitats being more strongly affected by fishing. Sessile and low mobility biota with longer life-spans such as sponges, soft corals and bivalves took much longer to recover after fishing (>3 year) than mobile biota with shorter life-spans such as polychaetes and malacostracans (<1 year). This meta-analysis provides insights into the dynamics of recovery. Our estimates of depletion along with estimates of recovery rates and large-scale, high-resolution maps of fishing frequency and habitat will support more rigorous assessment of the environmental impacts of bottom-contact gears, thus supporting better informed choices in trade-offs between environmental impacts and fish production.
Global analysis of depletion and recovery of seabed biota after bottom trawling disturbance
Hiddink, Jan Geert ; Jennings, Simon ; Sciberras, Marija ; Szostek, Claire L. ; Hughes, Kathryn M. ; Ellis, Nick ; Rijnsdorp, Adriaan D. ; Mcconnaughey, Robert A. ; Mazor, Tessa ; Hilborn, Ray ; Collie, Jeremy S. ; Pitcher, C.R. ; Amoroso, Ricardo O. ; Parma, Ana M. ; Suuronen, Petri ; Kaiser, Michel J. - \ 2017
Proceedings of the National Academy of Sciences of the United States of America 114 (2017)31. - ISSN 0027-8424 - p. 8301 - 8306.
logistic recovery model - systematic review - metaanalysis - impacts - trawling
Bottom trawling is the most widespread human activity affecting seabed habitats. Here, we collate all available data for experimental and comparative studies of trawling impacts on whole communities of seabed macroinvertebrates on sedimentary habitats and develop widely applicable methods to estimate depletion and recovery rates of biota after trawling. Depletion of biota and trawl penetration into the seabed are highly correlated. Otter trawls caused the least depletion, removing 6% of biota per pass and penetrating the seabed on average down to 2.4 cm, whereas hydraulic dredges caused the most depletion, removing 41% of biota and penetrating the seabed on average 16.1 cm. Median recovery times posttrawling (from 50 to 95% of unimpacted biomass) ranged between 1.9 and 6.4 y. By accounting for the effects of penetration depth, environmental variation, and uncertainty, the models explained much of the variability of depletion and recovery estimates from single studies. Coupled with
large-scale, high-resolution maps of trawling frequency and habitat, our estimates of depletion and recovery rates enable the assessment of trawling impacts on unprecedented spatial scales.
Estimating the sustainability of towed fishing-gear impacts on seabed habitats: a simple quantitative risk assessment method applicable to data-limited fisheries
Pitcher, C.R. ; Ellis, Nick ; Jennings, Simon ; Hiddink, Jan G. ; Mazor, Tessa ; Kaiser, Michel J. ; Kangas, Mervi I. ; Mcconnaughey, Robert A. ; Parma, Ana M. ; Rijnsdorp, Adriaan D. ; Suuronen, Petri ; Collie, Jeremy S. ; Amoroso, Ricardo ; Hughes, Kathryn M. ; Hilborn, Ray ; Freckleton, Robert - \ 2017
Methods in Ecology and Evolution 8 (2017). - ISSN 2041-210X - p. 472 - 480.
benthic fauna - depletion - ecological risk assessment - ecoystem-based fishery management - effects of trawling - recovery - resilience - sensivity - trawl footprints - vulnerability indicators
1. Impacts of bottom ﬁshing, particularly trawling and dredging, on seabed (benthic) habitats are commonly perceived to pose serious environmental risks. Quantitative ecological risk assessment can be used to evaluate actual risks and to help guide the choice of management measures needed to meet sustainability objectives. 2. We develop and apply a quantitative method for assessing the risks to benthic habitats by towed bottom-ﬁshing gears. The meth od is based on a simple eq uation for relative benthic status (RBS), derived by solving the logistic population growth equation for the equilibrium state. Estimating RBS requires only maps of ﬁshing intensity and habitat type – and parameters for impact and recovery rates, which may be taken from meta-analyses of multiple experimental studies of towed-gear impacts. The aggregate status of habitats in an assessed region is indicated by the distribution of RBS values for the region. The application of RBS is illustrated for a tropical shrimp-trawl ﬁshery. 3. The status of trawled habitats and their RBS value depend on impact rate (depletion per trawl), recovery rate and exposure to tra wling. In the shrimp-trawl ﬁshery region, gravel habitat was most sensitive, and though less exposed than sand or mudd y-sand, was most aﬀected overall (regional RBS = 91% relative to un-trawled RBS = 100%). Muddy-sand was less sensitive, and though relatively most exposed, was less aﬀected overall (RBS = 95%). Sand was most heavily trawled but least sensitive and least aﬀected overall (RBS = 98%). Region-wide , >94% of habitat area had >80% RBS because most tra wling and impacts were conﬁned to small areas. RBS was also applied to the region’s benthic invertebrate communities with similar results. 4. Conclu sions. Unlike qualitative or categorical trait-based risk assessments, the RBS method provides a quantitative estimate of status relative to an unimpacted baseline, with minimal requireme nts for input data. It could be applied to bottom-contact ﬁsh erie s world-wide, including situations where detailed data on characteristics of seabed habitats, or the abundance of seabed fauna are not available. The approach supports assessment against sustainability criteria and evaluation of alternative management strategies (e.g. closed areas, eﬀort management, gear modiﬁcations).
Indirect effects of bottom fishing on the productivity of marine fish
Collie, Jeremy ; Hiddink, Jan Geert ; Kooten, Tobias van; Rijnsdorp, Adriaan D. ; Kaiser, Michel J. ; Jennings, Simon ; Hilborn, Ray - \ 2017
Fish and Fisheries 18 (2017)4. - ISSN 1467-2960 - p. 619 - 637.
Beam trawls - Benthic disturbance - Dredges - Fish yield - Otter trawl
One quarter of marine fish production is caught with bottom trawls and dredges on continental shelves around the world. Towed bottom-fishing gears typically kill 20-50 per cent of the benthic invertebrates in their path, depending on gear type, substrate and vulnerability of particular taxa. Particularly vulnerable are epifaunal species, which stabilize the sediment and provide habitat for benthic invertebrates. To identify the habitats, fisheries or target species most likely to be affected, we review evidence of the indirect effects of bottom fishing on fish production. Recent studies have found differences in the diets of certain species in relation to bottom fishing intensity, thereby linking demersal fish to their benthic habitats at spatial scales of ~10 km. Bottom fishing affects diet composition and prey quality rather than the amount of prey consumed; scavenging of discarded by-catch makes only a small contribution to yearly food intake. Flatfish may benefit from light trawling levels on sandy seabeds, while higher-intensity trawling on more vulnerable habitats has a negative effect. Models suggest that reduction in the carrying capacity of habitats by bottom fishing could lead to lower equilibrium yield and a lower level of fishing mortality to obtain maximum yield. Trawling effort is patchily distributed - small fractions of fishing grounds are heavily fished, while large fractions are lightly fished or unfished. This patchiness, coupled with the foraging behaviour of demersal fish, may mitigate the indirect effects of bottom fishing on fish productivity. Current research attempts to scale up these localized effects to the population level.
Amazing grazing : Border Collie
Livestock Research, - \ 2013
Genetic variances, trends and mode of inheritance for hip and elbow dysplasia in Finnish dog populations
Mäki, K. ; Groen, A.F. ; Liinamo, A.E. ; Ojala, M. - \ 2002
Animal Science 75 (2002). - ISSN 1357-7298 - p. 197 - 207.
german-shepherd dogs - bernese mountain dogs - control program - cost-analysis - heritability - prevalence - rottweilers - retrievers - arthrosis - selection
The aims of this study were to assess genetic variances, trends and mode of inheritance for hip and elbow dysplasia in Finnish dog populations. The influence of time-dependent fixed effects in the model when estimating the genetic trends was also studied. Official hip and elbow dysplasia screening records of 42 421 dogs from seven breeds were analysed with REML. To investigate the mode of inheritance of hip and elbow dysplasia, trait distributions, genetic variances and regressions of offspring phenotypes on parental predicted breeding values were studied separately in males and in females. Genetic trends for hip dysplasia between the years 1983 and 1998 were favourable only in the Rottweiler. In elbow dysplasia, the trends were favourable after the year 1992 in all the four breeds studied but the overall changes were small. The reason for this seemed to be negligible selection pressure against these traits. Time-dependent fixed effects in the model had an influence on the estimated genetic trends, resulting either in a more negative or more positive genetic trend compared with the model from which the time-dependent effects were removed. Mitochondrial or sex-linked inheritance did not seem likely in the expression of hip and elbow dysplasia in the populations studied. Regression coefficients of offspring phenotypes on estimated parental breeding values were approximately equal to their expected value in a situation with equal parental contribution. Furthermore, the phenotypic frequency distributions of hip and elbow dysplasia grades were similar among males and females in each breed studied. No indication of major genes was found in the offspring frequency distributions within individual sires. According to these Finnish data, mode of inheritance for both hip and elbow dysplasia is polygenic (quantitative) with equal expression of the genes from both parents, although the estimates of heritability for hip dysplasia in the Rough Collie and for elbow dysplasia in the German Shepherd and the Golden Retriever were somewhat different in males compared with females.