Estimated catch and mortality of sea turtles from the East Coast Otter Trawl Fishery of Queensland, Australia

Identification of threats is a standard component of conservation planning and the ability to rank threats may improve the allocation of scarce resources in threat-mitigation programs. For vulnerable and endangered sea turtles in Australia, vessel strike is recognised as an important threat but its severity relative to other threats remains speculative. Documented evidence for this problem is available only in stranding records collected by the Queensland Environment Protection Authority. With the authority’s support we assessed the scope and quality of the data and analysed vessel-related records. We found adequate evidence that during the period 1999–2002 at least 65 turtles were killed annually as a result of collisions with vessels on the Queensland east coast. This level of mortality appears broadly comparable to that recorded in the Queensland East Coast Trawl Fishery before the introduction of mandatory turtle-exclusion devices in that fishery. Green turtles (Chelonia mydas) comprised the majority of vessel-related records, followed by loggerhead turtles (Caretta caretta), and 72% of cases concerned adult or subadult turtles. The majority of vessel-related records came from the greater Moreton Bay area, followed by Hervey Bay and Cleveland Bay. The waters of all three areas are subject to variable levels of commercial and recreational vessel traffic, and their shores are both populated and unpopulated.

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Quantifying long-term discards from Queensland’s (Australia) east Coast otter trawl fishery

ICES Journal of Marine Science ◽

10.1093/icesjms/fsz205 ◽

2019 ◽

Vol 77 (2) ◽

pp. 680-691 ◽

Cited By ~ 1

Author(s):

Na Wang ◽

Anthony J Courtney ◽

Matthew J Campbell ◽

Wen-Hsi Yang

Keyword(s):

East Coast ◽

Fishing Effort ◽

Otter Trawl ◽

Lunar Phase ◽

Trawl Fishery ◽

Bycatch Reduction ◽

Fishing Sector ◽

Trawl Fishing ◽

Fishery Discards

Abstract This article estimated the weight of annual discards in the Queensland east coast otter trawl fishery. Discards data were analysed using three generalized linear mixed models to derive adjusted discard rates, expressed as kg per retained catch, kg per boat day, and kg per area swept by trawls, respectively. Model explanatory terms included trawl fishing sector, presence/absence of bycatch reduction devices (BRDs), lunar phase, and whether the data were obtained from commercial vessels during their normal fishing activities or during research charters. Adjusted discard rates were then used to derive three estimates of annual discards and the average used to examine a long-term discard trends from 1988 to 2014. Total discards declined significantly from a peak of approximately 67 000 t in 1997 to approximately 21 000 t from 2011 to 2014, largely due to a decline in fishing effort, and to a lesser degree, the effects of BRDs that were mandated in the fishery in the early 2000s.

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Reproductive parameters of rhinobatid and urolophid batoids taken as by-catch in the Queensland (Australia) east coast otter-trawl fishery

Journal of Fish Biology ◽

10.1111/jfb.13020 ◽

2016 ◽

Vol 89 (2) ◽

pp. 1208-1226 ◽

Cited By ~ 3

Author(s):

P. M. Kyne ◽

A. J. Courtney ◽

I. P. Jacobsen ◽

M. B. Bennett

Keyword(s):

East Coast ◽

Otter Trawl ◽

Reproductive Parameters ◽

Trawl Fishery ◽

By Catch

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Use of avoidance behaviours to reduce the economic impacts of the EU Landing Obligation: the case study of a mixed trawl fishery

ICES Journal of Marine Science ◽

10.1093/icesjms/fsz032 ◽

2019 ◽

Vol 76 (6) ◽

pp. 1554-1566

Author(s):

Fabien Pointin ◽

Fabienne Daurès ◽

Marie-Joëlle Rochet

Keyword(s):

Temporal Distribution ◽

Grid Method ◽

Fishing Effort ◽

Economic Losses ◽

Otter Trawl ◽

Trawl Fishery ◽

Nested Grid ◽

Fishing Practices ◽

The Eu

Abstract The EU Landing Obligation (LO) is designed to reduce bycatch (i.e. unwanted catch) through more selective fishing practices, such as avoidance behaviours which consist in allocating fishing effort to other species, fishing grounds or seasons. Incentives for fishers to change their behaviours depend on their economic performances as well as their ability to avoid bycatch. Changes in economic performances under the LO are evaluated based on cost and revenue equations. The nested grid method is then used to explore the spatial and temporal distribution of landings and discards, and to suggest alternative effort allocation to avoid bycatch. This article is focussed specifically on the French otter trawl fishery in the eastern English Channel and southern North Sea. Results suggest that under the LO the choke species problem will curtail fishing activities earlier in the year, leading to significant economic losses. In the absence of significant quota top-ups (at least 75%), a change in fishing practices consisting in reducing overall bycatch by 30% is insufficient to reduce losses. With a particular attention to choke species, more economically efficient avoidance strategies can be found thanks to the nested grid method.

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Reflex impairment, physiological stress, and discard mortality of European plaice Pleuronectes platessa in an otter trawl fishery

ICES Journal of Marine Science ◽

10.1093/icesjms/fsx004 ◽

2017 ◽

Vol 74 (6) ◽

pp. 1660-1671 ◽

Cited By ~ 11

Author(s):

Caroline Methling ◽

Peter V. Skov ◽

Niels Madsen

Keyword(s):

Physiological Stress ◽

Plasma Osmolality ◽

Control Fish ◽

Otter Trawl ◽

Air Exposure ◽

Trawl Fishery ◽

Physiological Variables ◽

Discard Mortality ◽

Fisheries Policy ◽

Short Term Mortality

Abstract The reformed European Common Fisheries Policy introduced a discard ban, with a possibility of exempting species where a high discard survival can be demonstrated. This necessitates a validation of the methods used for estimating the discard mortality of candidate species. In this study, we assess whether reflex impairment can predict short-term mortality in commercially trawled European plaice upon landing and after air exposure of up to 90 min. Sub-lethal stress was assessed by a suite of physiological variables. Over a 10-day period, mortality was monitored for a total of 199 plaice following trawl and air exposure of varying duration, and for 50 control fish scored for reflex impairment on board the vessel. Mortality was only observed in fish exposed to air for >60 min, and averaged 11.1% (95% CI = 7.1–16.3%). Reflex impairment was found to be a significant (P < 0.001) predictor of mortality in a generalized linear model, excluding other initially included variables by using a stepwise method. Plasma cortisol, haematocrit, and plasma osmolality all indicated a profound and increasing level of stress with air exposure, accompanied by a near depletion of muscle phosphocreatine and nucleotides. Fishing site had an unexpected, but significant (p < 0.05) effect on stress levels, which was also reflected in reflex impairment and mortality. Based on these findings, a possible exemption from the discard ban should include considerations on the duration of air exposure.

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Stimulating release of undersized fish through a square mesh panel in the Basque otter trawl fishery

Fisheries Research ◽

10.1016/j.fishres.2019.105431 ◽

2020 ◽

Vol 224 ◽

pp. 105431

Author(s):

Elsa Cuende ◽

Luis Arregi ◽

Bent Herrmann ◽

Manu Sistiaga ◽

Iñigo Onandia

Keyword(s):

Otter Trawl ◽

Trawl Fishery

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The recovery of Atlantic halibut: a large, long-lived, and exploited marine predator

ICES Journal of Marine Science ◽

10.1093/icesjms/fsv266 ◽

2016 ◽

Vol 73 (4) ◽

pp. 1104-1114 ◽

Cited By ~ 7

Author(s):

M. Kurtis Trzcinski ◽

W. Don Bowen

Keyword(s):

Gadus Morhua ◽

Assessment Model ◽

Minimum Size ◽

Otter Trawl ◽

Atlantic Halibut ◽

High Biomass ◽

Total Allowable Catch ◽

Marine Predator ◽

Trawl Fishery ◽

Management Actions

Abstract Atlantic halibut (Hippoglossus hippoglossus) have a long history of exploitation in the Northwest Atlantic and have gone through several periods of high biomass followed by a population crash. An assessment model using data collected on the Scotian Shelf and southern Grand Banks shows that the population peaked in 1984, then decreased sharply to a low in 1993. Several management measures were taken during the decline, including reductions in total allowable catch and a minimum size limit. Concurrently, removals by the otter trawl fishery were drastically reduced following the collapse of the cod (Gadus morhua) fishery. In 2003, recruitment increased and continued to be high for 6 years. Fishing mortality rates were moderate in the late 1990s and 2000s and the population increased. By 2009, the Atlantic halibut population was highly productive with both high biomass and high levels of recruitment. The coincidence in the timing of population recovery and management actions indicates that effective management contributed to the recovery of Atlantic halibut.

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