Active Forum Topics

Field Study 756

Study Type
Field study in the wild
Location
Cornwall
Target catch
None reported
Effect on bycatch species
There was a significant difference in the number of porpoise clicks between nets with and without pingers, but the extent of displacement could not be determined. No evidence of habituation to the pingers.
Effect on target catch
None reported
Reduction technique
Fishing Gear

Field Study 756

Study Type
Field study in the wild
Location
Cornwall
Target catch
None reported
Effect on bycatch species
There was a significant difference in the number of porpoise clicks between nets with and without pingers, but the extent of displacement could not be determined. No evidence of habituation to the pingers.
Effect on target catch
None reported
Reduction technique
Fishing Gear

Decreased feeding ability of a minke whale (Balaenoptera acutorostrata) with entanglement-like injuries

Submitted by BrianKot on

This investigation details an unusual encounter with a lunge-feeding minke whale with fresh entanglement-like injuries to its head and ventral pouch.  It also discusses results from a short-term comparative study that tested whether the whale fed differently than five uninjured minke whales feeding in the same area.  Collectively, this study: 1) quantifies how much a rope-like injury can restrict the expansion of a minke's ventral pouch while feeding, 2) provides the first minke whale lunge-feeding velocities from a photogrammetric method using digital video, and 3) describes a ne

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Interactions of Patagonian toothfish fisheries with killer and sperm whales in the Crozet Islands exclusive economic zone: an assessment of depredation levels and insights on possible mitigation strategies

Submitted by Kate McClellan on

The Patagonian toothfish longline fishery has high levels of depredation by killer and sperm whales, which puts the whales at risk of being bycatch. Observations from 2003 to 2008 revealed significant variations of interaction rates with killer whales between vessels, suggesting the influence of operational factors on vessel interaction and depredation. When killer whales were absent at the beginning of the line hauling process, short lines (<5,000 m) provided higher yield and were significantly less impacted by depredation than longer lines.

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Whale Shark

Species
Rhincodon typus

Historically, the whale shark has been hunted for its meat and liver oil. Whale shark fins are considered inferior in quality and the species is generally not targeted for its fins, although a market for them does exist in Asia due to their massive size (Norman 2005). Despite the fact that there is a paucity of data regarding whale shark bycatch, it is believed that the species most commonly becomes entangled in purse seines, longlines, and gillnets, particularly set nets.

Distribution
Tropical and warm temperate waters 30˚N to 35˚S, with the exception of the Mediterranean Sea
Population
Decreasing
IUCN Status
Vulnerable
Type
Fish
Bycatch Threat
Gillnets, purse seines, longlines

Thorny skate

Species
Amblyraja radiata

Data from the Northwest Atlantic suggests that the thorny skate began declining in the early 1980s and accelerated in the early 1990s (Burgess et al 2005). In US waters, dredging for scallops also poses a risk (Packer et al 2003). Additionally, a targeted fishery for the species emerged in Canada in order to meet a growing European demand for skate wings (Kulka et al 2009). Bycatch in Canadian waters occurs on the Scotian Shelf, though landings do not equal those of the targeted fishery (Kulka et al 2009).

Distribution
Northeast and Northwest Atlantic
Population
Decreasing
IUCN Status
Vulnerable
Type
Fish
Bycatch Threat
Trawls, dredges

Australian sea lion

Species
Neophoca cinerea

The Australian sea lion population decreased due to harvests in the 17th and 18th centuries and traditional subsistence hunting by aborigines (Goldsworhty & Gales 2008). Isolated reports of deliberate killings have persisted into the 21st century as well (DEWHA 2010). Although the species is now protected by Australian law throughout its range, recovery towards pre-sealing levels has been minimal (Goldsworthy and Gales 2008; AFMA 2010).

Distribution
Southern and southwestern Australian waters
Population
~14700
IUCN Status
Endangered
Type
Mammal
Bycatch Threat
Gillnets, trawls, traps and pots

Study on the methods to mitigate the bycatch of juvenile bigeye tuna by introducing Double-FADs with light stimulus for tuna purse seine fishery in the Western and Central Pacific Ocean

Submitted by morgaac on

A Double-FAD design was tested for it's ability to mitigate the incidental capture of bigeye tuna in purse fisheries of the Western and Central Pacific Ocean.  The design consisted of two separate FADs with underwater light stimuli attached.  The number of animals caught was not large enough to conduct statistical analyses, but based on the weight of fish, the size proportion of skipjack, yellowfin and bigeye was bigger using the Double-FAD design comapared to the normal design.

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Field Study 769

Study Type
Field study in the wild
Location
Papua New Guinea and Solomon Islands
Target catch
Skipjack and yellowfin tuna
Effect on bycatch species
Double-FADS caught larger bigeye tunas but the catch rate was slightly less than on normal FAD sets.
Effect on target catch
Fewer skipjack tuna were caught by number and weight. Yellowfin tuna catch was higher.
Bycatch species
Reduction technique
Fishing Gear

Field Study 769

Study Type
Field study in the wild
Location
Papua New Guinea and Solomon Islands
Target catch
Skipjack and yellowfin tuna
Effect on bycatch species
Double-FADS caught larger bigeye tunas but the catch rate was slightly less than on normal FAD sets.
Effect on target catch
Fewer skipjack tuna were caught by number and weight. Yellowfin tuna catch was higher.
Bycatch species
Reduction technique
Fishing Gear

Field Study 769

Study Type
Field study in the wild
Location
Papua New Guinea and Solomon Islands
Target catch
Skipjack and yellowfin tuna
Effect on bycatch species
Double-FADS caught larger bigeye tunas but the catch rate was slightly less than on normal FAD sets.
Effect on target catch
Fewer skipjack tuna were caught by number and weight. Yellowfin tuna catch was higher.
Bycatch species
Reduction technique
Fishing Gear