A risk-assessment approach to evaluating the significance of seal bycatch in two Australian fisheries

Goldsworthy, Simon; Page, Brad

doi:10.1016/j.biocon.2007.07.010

Cited by 70 publications

(62 citation statements)

References 22 publications

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“…The present estimate exceeds 3 recent estimates of pup abundance in SA by at least 16%: 2115 by Goldsworthy et al (2003), 1994by McKenzie et al (2005 and 2674 by Goldsworthy & Page (2007). The increase follows recognition of new breeding colonies, targeting visits for estimating pup numbers to coincide with maximum numbers ashore and incorporating a more recent estimate for Dangerous Reef (where numbers increased substantially).…”

Section: Comparison With Previous Pup Abundance Estimatescontrasting

confidence: 52%

“…Only small numbers of pups have been reported at several of the 48 breeding sites, highlighting the need to maintain their conservation status. Modelling by Goldsworthy & Page (2007) indicated that small colonies are particularly susceptible to extinction, even in the absence of any anthropogenic mortality such as that caused by fishery bycatch.…”

Section: Breeding Sites Of the Australian Sea Lion In Samentioning

confidence: 99%

“…For the population of Australian sea lions in SA, this leads to an overall estimate of 12 726 animals using the multiplier 4.08 derived by Goldsworthy & Page (2007). With the addition of 503 pups from WA (summarised by Goldsworthy et al 2009b), a minimum of 3622 pups are born per breeding cycle across the species' range, 86% of which are in SA and 14% in WA.…”

Section: Comparison With Previous Pup Abundance Estimatesmentioning

confidence: 99%

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Australian sea lions Neophoca cinerea at colonies in South Australia: distribution and abundance, 2004 to 2008

Shaughnessy¹,

Goldsworthy

Hamer

et al. 2011

Endang. Species. Res.

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The Australian sea lion Neophoca cinerea is an endemic species listed as vulnerable under the Commonwealth 'Environment Protection and Biodiversity Conservation Act' and as Endangered by IUCN. Assessing its abundance is difficult because of its supra-annual (17 to 18 mo) breeding cycle, and pupping seasons that are extended (about 6 mo but varying between colonies) and asynchronous in their timing between colonies. Based mainly on surveys at most sites in South Australia (SA) between 2004 and 2008, and information from the literature, estimates of abundance are provided for 39 breeding colonies and 9 haulout sites where pups are recorded occasionally. From this study it is estimated that in SA, 3119 Australian sea lion pups are born per breeding cycle, an increase on former estimates by at least 16% resulting from recognition of new breeding colonies, targeting surveys to coincide with maximum pup numbers and using mark-recapture procedures at some colonies. With the addition of 503 pups in Western Australia, the overall estimate of pup abundance for the species is 3622. This leads to an estimate of 14 780 animals using the multiplier 4.08. Trend data for the Seal Bay colony on Kangaroo Island indicated that pup numbers decreased at 0.54% yr -1 in the 22 yr (16 pupping seasons) from 1985 to 2007. A cause of the decrease is believed to be bycatch in the demersal shark gillnet fishery, which overlaps with sea lion foraging areas nearby. Area closures declared during 2010 within several km of all Australian sea lion breeding sites in SA should reduce the incidence of bycatch mortality.

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Section: Comparison With Previous Pup Abundance Estimatescontrasting

confidence: 52%

Section: Breeding Sites Of the Australian Sea Lion In Samentioning

confidence: 99%

Section: Comparison With Previous Pup Abundance Estimatesmentioning

confidence: 99%

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Australian sea lions Neophoca cinerea at colonies in South Australia: distribution and abundance, 2004 to 2008

Shaughnessy¹,

Goldsworthy

Hamer

et al. 2011

Endang. Species. Res.

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“…This comparatively slow individual reproductive rate combined with small colony sizes across a wide geographic range means that the Australian sea lion is highly susceptible to stochastic processes and increases in mortality rates. Bycatch in demersal gillnet fisheries is already a significant cause of increased mortality (Goldsworthy and Page, 2007;Hamer et al, 2013) and vulnerability to environmental change is a looming long-term threat (Schumann et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The Limits of Dispersal: Fine Scale Spatial Genetic Structure in Australian Sea Lions

et al. 2016

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Describing patterns of connectivity throughout a species range is critical to conservation management. In common with other mammals, pinnipeds typically display male-biased dispersal. Earlier studies using mitochondrial DNA showed that the endangered Australian sea lion (Neophoca cinerea) exhibits extreme matrilineal structure throughout its range. If male dispersal were similarly restricted, most breeding colonies may not receive sufficient levels of new genetic variation to buffer against risks associated with inbreeding and environmental change. To address these concerns we used 16 microsatellite loci to obtain a more highly resolving measure of genetic structure among colonies and determine whether dispersal is male-biased. We found that both male and female Australian sea lions are highly philopatric with limited dispersal. Within those constraints, when animals disperse between close colonies (<110 km) there is a tendency for males to move further than females. Our findings are intriguing considering the dispersal potential of Australian sea lions and the unique asynchronous breeding opportunities that might be expected to provide an incentive for male reproductive movements between geographically close colonies.

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“…Current methodologies in species habitat modeling, which have been useful to understand species−environment relationships and habitat preference, have been combined with fisheries effort and interaction rates to produce spatial risk assessments for species such as seabirds (Cuthbert et al 2005(Cuthbert et al , 5ydelis et al 2011, sea turtles (Murray & Orphanides 2013), and marine mammals (Goldsworthy & Page 2007. A recently published study by D' Souza et al (2013) showed long-term trends of heightened risk of dugong extinction by anthropogenic factors in areas historically known as optimal foraging habitat.…”

Section: Introductionmentioning

confidence: 99%

Modeling habitat and bycatch risk for dugongs in Sabah, Malaysia

Briscoe¹,

Hiatt²,

Lewison³

et al. 2014

Endang. Species. Res.

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Bycatch of marine megafauna in fishing gear is a problem with global implications. Bycatch rates can be difficult to quantify, especially in countries where there are limited data on the abundance and distribution of coastal marine mammals, the distribution and intensity of fishing effort, and coincident interactions, and limited bycatch mitigation strategies. The dugong Dugong dugon is an IUCN-listed Vulnerable species found from the eastern coast of Africa to the western Pacific. As foragers of seagrass, they are highly susceptible to bycatch in small-scale fisheries. To address the knowledge gaps surrounding marine mammal bycatch, we used existing survey and fishing effort data to spatially characterize the risk of bycatch for this species. Using Sabah, Malaysia, as a case study, we employed presence-only modeling techniques to identify habitat associations of dugongs using a maximum entropy distribution model (MaxEnt) based on published sightings data and several geophysical parameters: coastal distance, depth, insolation, and topographic openness. Model outputs showed distance from the coast as the highest-contributing variable to the probability of dugong presence. Results were combined with previously published fishing effort maps of this area to develop a predictive bycatch risk surface. Our analyses identified several areas of high risk where dugong surveys were conducted, but also identified high-risk areas in previously unsurveyed locations. Such methods can be used to direct field activities and data collection efforts and provide a robust template for how existing sightings and fishing effort data can be used to facilitate conservation action in data-limited regions.

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A risk-assessment approach to evaluating the significance of seal bycatch in two Australian fisheries

Cited by 70 publications

References 22 publications

Australian sea lions Neophoca cinerea at colonies in South Australia: distribution and abundance, 2004 to 2008

Australian sea lions Neophoca cinerea at colonies in South Australia: distribution and abundance, 2004 to 2008

The Limits of Dispersal: Fine Scale Spatial Genetic Structure in Australian Sea Lions

Modeling habitat and bycatch risk for dugongs in Sabah, Malaysia

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