The impact of fish trawls on megabenthos (sponges) on the north-west shelf of Australia

Wassenberg, T.J.; Dews, GJ; Cook, Shannon

doi:10.1016/s0165-7836(01)00382-4

Cited by 67 publications

(50 citation statements)

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“…Therefore, all of the biogenic structures used to parameterize our models were coded as presence or absence before analyses. We also considered that trawl nets sampled sponges differentially (see Wassenberg et al, 2002), integrating their actual distribution over trawlable bottom for the duration of the trawl haul. Therefore, we consider the coding of biogenic structures in our trawl catches as presence-absence factors to be a conservative measure of their occurrence.…”

Section: Invertebrate Datamentioning

confidence: 99%

“…Four candidate models for the prediction of presence or conditional abundance of juvenile and adult Pacific ocean perch underwent backward stepwise term selection (Weinberg and Kotwicki, 2008;Zuur et al, 2009). …”

Section: Modelingmentioning

confidence: 99%

“…In this study, we consider sponge morphology from a functional perspective (the "fish-eye view") of the structure it provides in the habitat. An added benefit of grouping the sponges by this functional morphology is to foster comparability of sponge assemblages among survey years by downplaying the differences in identification attributable to differing levels of expertise among the field biologists.Sponges and corals are vulnerable to removal or damage by fishing gear (Engel and Kvitek, 1998;Freese et al, 1999; Freese, 2001;Wassenberg et al, 2002; Stone et al, 2011). In addition, these sessile invertebrates are long lived and have limited larval dispersal and reproductive potential (Andrews et al, 2002).…”

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confidence: 99%

“…Consequently, we combined depth and temperature into a bivariate interaction term in the GAM. To determine interdependency of sponge morph, bryozoan, and coral presence-absence factors, we computed Pearson's coefficient of mean square contingency (Φ; Zar, 1984), found that for all pairwise comparisons |Φ| was <0.50, and consequently included each biogenic presence-absence factor as an independent predictor in the GAM.Four candidate models for the prediction of presence or conditional abundance of juvenile and adult Pacific ocean perch underwent backward stepwise term selection (Weinberg and Kotwicki, 2008; Zuur et al, 2009). …”

mentioning

confidence: 99%

“…Sponges and corals are vulnerable to removal or damage by fishing gear (Engel and Kvitek, 1998;Freese et al, 1999; Freese, 2001;Wassenberg et al, 2002; Stone et al, 2011). In addition, these sessile invertebrates are long lived and have limited larval dispersal and reproductive potential (Andrews et al, 2002).…”

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confidence: 99%

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Correlating environmental and biogenic factors with abundance and distribution of Pacific ocean perch (Sebastes alutus) in the Aleutian Islands, Alaska

Laman¹,

Kotwicki²,

Rooper³

2015

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Abstract-In the Aleutian Islands, patterns of distribution and abundance of Pacific ocean perch (Sebastes alutus) are influenced by oceanographic processes and biogenic structures. We used generalized additive modeling (GAM) to examine relationships between these predictors and patterns of settled juvenile and adult distribution and abundance from bottom trawl surveys conducted from 1997 through 2010. Depth, temperature, and location had the greatest influence, and biogenic structures co-occurring with this species improved predictions. Model results confirmed previously reported depth-and temperaturedependent patterns of Pacific ocean perch and revealed the elevated presence and abundance of this fish in proximity to Aleutian passes. Adults were more common and abundant in deeper (~225 m) water than were juveniles (~150 m), and the probability of encountering either life stage increased in the presence of fan-and ball-shaped sponges over moderate slopes and decreased with increasing tidal velocities. The GAMs accounted for one-quarter of the deviance for juvenile presenceabsence (24.9%) and conditional abundance (25.0%) and accounted for 38.7% and 42.5% of the deviance for the same adult response variables. Although depth, temperature, and location were the dominant predictor variables of both juvenile presence and abundance, our results indicate that biogenic structures that provide vertical structure in otherwise lowrelief, trawlable habitats may represent refugia for Pacific ocean perch juveniles and adults.Describing essential fish habitat (EFH), defined by the Magnuson-Stevens Fishery Conservation and Management Act (Magnuson-Stevens Act) as "those waters and substrate necessary to fish for spawning, breeding, feeding or growth to maturity," has been the focus of much recent habitat research. Laidig et al. (2009) used the Delta submersible to conduct visual surveys on the central California shelf and found that demersal fishes associated with boulder and cobble substrata occurred in greater numbers than they did with mud or brachiopod beds. Other studies have observed denser and more diverse assemblages of rockfishes in the presence of increased boulder coverage (Marliave and Challenger, 2009) or in association with rocky ridges (Rooper et al., 2010). Greene et al. (2011) demonstrated that rugged seafloor geomorphologies in southeast Alaska can be used to identify suitable habitat for demersal shelf rockfish (Sebastes spp.). Living substrata can also modify seafloor habitats in ways that impact EFH. Others have considered biogenic structures, such as sponges, corals, and bryozoans, to be important habitat-forming organisms in Alaska Malecha et al., 2005; Stone et al., 2011) and other waters (e.g., Barthel, 1997 [Weddell Sea]; Beazley et al., 2013 [the northwest Atlantic]; and Coker et al., 2014 [warm-water coral reefs]). In this study, we attempt to add to the growing body of knowledge used to identify and describe EFH for species of Sebastes in Alaska.The Resource Assessment and Conservation Engin...

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Section: Invertebrate Datamentioning

confidence: 99%

Section: Modelingmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Correlating environmental and biogenic factors with abundance and distribution of Pacific ocean perch (Sebastes alutus) in the Aleutian Islands, Alaska

Laman¹,

Kotwicki²,

Rooper³

2015

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Fishing gear effects and ecology of the sea whip (Halipteris willemoesi (Cnidaria: Octocorallia: Pennatulacea)) in British Columbia, Canada: preliminary observations

Troffe

Levings

Piercey

et al. 2005

Aquatic Conservation

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ABSTRACT1. We conducted a preliminary study of the effects of a shrimp beam trawl and prawn traps on sea whips (Halipteris willemoesi (Cnidaria: Octocorallia: Pennatulacea)) at two bays on Clio Channel, south central coast of British Columbia, Canada. Video and grabs surveys were conducted to estimate abundance and make observations on sea whips and their habitat.2. No adult sea whips were caught in six beam trawls. In 600 prawn (Pandalus platyceros) trap sets at Turnour Bay, 30 sea whips were found entangled in the gear and of these 50% of the colonies were damaged. The length of broken sea whips ranged from 0.09 to 1.03 m. At Turnour Bay, the density of adults observed in video surveys ranged from 7.1 to 14.3 m À2. Juvenile density in grab samples ranged from 53 to 123 m À2 and a few adults were also caught. The lengths of intact adult sea whips caught in traps and grabs ranged from 0.20 to 1.98 m and juveniles from 0.3 to 0.7 cm.3. Fewer adult sea whips (50.1 m À2 ) were seen in Bones Bay, where sediments were muddier (grain size 50.25 mm: 84.6 to 97.2%) relative to Turnour Bay (grain size 50.25 mm: 71.4 to 85.9%). Bottom water characteristics at the two bays were similar. Seasonal temperature range was 7.5-8.48C, salinity 30.63-31.49 psu, and dissolved oxygen 2.76-5.97 mg L À1 . Differences in sediment characteristics and food availability may have been a factor influencing differences in abundance of sea whips between the two bays.4. Further data are needed to investigate the effects of trawling and trapping on sea whips, as sample sizes were small in the present study and only two gear types were evaluated. Studies of effects of otter trawling and heavier traps, such as those used for Dungeness crab (Cancer magister), are warranted.

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Towed camera imagery and benthic sled catches provide different views of seamount benthic diversity

Williams

Althaus

Schlacher

2015

Limnology & Ocean Methods

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Because benthic ecosystems of seamounts support vulnerable biota that are increasingly threatened by mining and fishing, assessments of ecological conditions and impacts are important to balance resource extraction with biological conservation. These assessments rely on ecological metrics generated from physical collections of fauna with sleds or similar gears, or by surveying the seafloor with cameras. If different gears (sled or cameras) "sample" the benthos differently, derived ecological metrics will also differ. Here, we test this hypothesis by comparing data provided by a robust benthic sled and a quantitative towed camera from colocated transects on seamounts off Tasmania (Australia). Our comparison showed these tools provide complementary but not interchangeable metrics of seamount benthic diversity and abundance. Choice of sampler(s) needs to be determined by survey objectives and consider the following trade-offs: (1) sleds will detect more species than image-based techniques; (2) specimens obtained by physical sampling (sleds) can considerably extend the scope of ecological analysis through genetic, isotopic, and other analysis of biological material not available from camera surveys; (3) image-derived data provide significantly and often considerably, higher estimates of megabenthos abundance; and (4) environmental impacts are much lower in camera surveys and therefore are arguably more ethical-an important consideration when repeat surveys are required, especially in areas of high conservation importance or heightened sensitivity. Undersampling by sleds of corals and sponges is an important aspect of gear selectivity because these taxa are consistently prominent indicators in protocols that identify benthic "vulnerable marine ecosystems" in assessments of human impacts.

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The impact of fish trawls on megabenthos (sponges) on the north-west shelf of Australia

Cited by 67 publications

References 10 publications

Correlating environmental and biogenic factors with abundance and distribution of Pacific ocean perch (Sebastes alutus) in the Aleutian Islands, Alaska

Correlating environmental and biogenic factors with abundance and distribution of Pacific ocean perch (Sebastes alutus) in the Aleutian Islands, Alaska

Fishing gear effects and ecology of the sea whip (Halipteris willemoesi (Cnidaria: Octocorallia: Pennatulacea)) in British Columbia, Canada: preliminary observations

Towed camera imagery and benthic sled catches provide different views of seamount benthic diversity

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