Experimental Attempts to Reduce Predation by Harbor Seals on Out-Migrating Juvenile Salmonids

Yurk, Harald; Trites, Andrew W.

doi:10.1577/1548-8659(2000)129<1360:eatrpb>2.0.co;2

Cited by 94 publications

(82 citation statements)

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“…Taking into account the mixed long-term results acoustic deterrents have had in driving seals away from fishing nets, and their cost (Pemberton & Shaughnessy 1993, Yurk & Trites 2000, Fjälling et al 2006, as well as the large number of fishers and the large extent of the area in which such conservation actions would have to take place, we do not believe that the use of such devices represents a viable solution to the problem of accidental entanglement of Mediterranean monk seals in fishing gear.…”

Section: Discussionmentioning

confidence: 90%

Assessing accidental entanglement as a threat to the Mediterranean monk seal Monachus monachus

Karamanlidis¹,

Androukaki²,

Adamantopoulou³

et al. 2008

Endang. Species Res.

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The Mediterranean monk seal Monachus monachus is the most endangered seal in the world with < 600 ind. currently surviving. The species faces a number of threats to its survival: accidental entanglement has been identified as one of the most important amongst them. Here we made the first attempt to systematically describe the nature of this threat and assess its impact on Mediterranean monk seal populations. We based our study on information from an extensive literature review, questionnaires carried out in various locations in Greece and necropsies performed in Greece and in the Madeira Islands, Portugal. Our results indicate that accidental entanglement has been, and still is, a major threat to the species in its main distribution area in the northeastern Mediterranean, and that this threat may increase throughout the seal's range. Accidental entanglement occurs mainly with fishing nets, and affects mostly sub-adult seals. Short-term conservation actions should include the identification of critical pupping sites and their protection through the establishment and enforcement of protective measures. A long-term course of action will require detailed knowledge of the causes of accidental entanglement of Mediterranean monk seals in fishing gear.KEY WORDS: Endangered species · Mediterranean monk seal · Accidental entanglement · Conservation · Seal-fishery interactions · Greece · Madeira

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Section: Discussionmentioning

confidence: 90%

Assessing accidental entanglement as a threat to the Mediterranean monk seal Monachus monachus

Karamanlidis¹,

Androukaki²,

Adamantopoulou³

et al. 2008

Endang. Species Res.

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“…Harbor seals forage opportunistically and shift diet seasonally based on prey availability (Lance et al 2012) and prey on steel head smolts in some locations (Laake et al 2002). In the Puntledge River, British Columbia, harbor seals adapted their foraging behavior to ambush migrating salmon smolts under a lighted bridge (Yurk & Trites 2000). Diet information on harbor porpoises in the Salish Sea indicates little or no predation on salmonids at any life stage, though data are temporally limited and only represent stranded animals (Walker et al 1998, Nichol et al 2013.…”

Section: Discussionmentioning

confidence: 99%

Multi-population analysis of Puget Sound steelhead survival and migration behavior

Moore¹,

Berejikian²,

Goetz³

et al. 2015

Mar. Ecol. Prog. Ser.

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Until recently, research on mortality of anadromous fishes in the marine environment was largely limited to estimates of total mortality and association with group characteristics or the environment. Advances in sonic transmitter technology now allow estimates of survival in discrete marine habitats, yielding important information on species of conservation concern. Previous telemetry studies of steelhead Oncorhynchus mykiss smolts in Puget Sound, Washington, USA indicated that approx. 80% of fish entering marine waters did not survive to the Pacific Ocean. The present study re-examined data from previous research and incorporated data from additional Puget Sound populations (n = 7 wild and 6 hatchery populations) tagged during the same period (2006−2009) for a comprehensive analysis of steelhead early marine survival. We used mark-recapture models to examine the effects of several factors on smolt survival and to identify areas of Puget Sound where mortality rates were highest. Wild smolts had higher survival probabilities in general than hatchery smolts, with exceptions, and wild smolts released in early April and late May had a higher probability of survival than those released in early and mid-May. Steelhead smolts suffered greater instantaneous mortality rates in the central region of Puget Sound and from the north end of Hood Canal through Admiralty Inlet than in other monitored migration segments. Early marine survival rates were low (16.0 and 11.4% for wild and hatchery populations, respectively) and consistent among wild populations, indicating a common rather than watershed-specific mortality source. With segment-specific survival information we can begin to identify locations associated with high rates of mortality, and identify the mechanisms responsible.

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“…A common finding is the significant number of farmed fish that predators can consume if afforded easy access to their prey (Adámek et al 2003;Yurk and Trites 2000). In an attempt to understand the dynamics of predation on commercial and recreational fishing, Dieperink (1995) investigated the foraging area of a large cormorant colony in a Danish fjord.…”

Section: Predatorsmentioning

confidence: 99%

Animal Welfare and Organic Aquaculture in Open Systems

Cottee

Petersan

2009

J Agric Environ Ethics

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The principles of organic farming espouse a holistic approach to agriculture that promotes sustainable and harmonious relationships amongst the natural environment, plants, and animals, as well as regard for animals' physiological and behavioral needs. However, open aquaculture systems-both organic and conventional-present unresolved and significant challenges to the welfare of farmed and wild fish, as well as other wildlife, and to environmental integrity, due to water quality issues, escapes, parasites, predator control, and feed-source sustainability. Without addressing these issues, it is unlikely that open net-pen aquaculture production can be compatible with the principles inherent to organic farming.

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Experimental Attempts to Reduce Predation by Harbor Seals on Out-Migrating Juvenile Salmonids

Cited by 94 publications

References 1 publication

Assessing accidental entanglement as a threat to the Mediterranean monk seal Monachus monachus

Assessing accidental entanglement as a threat to the Mediterranean monk seal Monachus monachus

Multi-population analysis of Puget Sound steelhead survival and migration behavior

Animal Welfare and Organic Aquaculture in Open Systems

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