Estimation of seabird bycatch for North Pacific longline vessels using design- and model-based methods

2006 ◽  
Vol 63 (8) ◽  
pp. 1878-1889 ◽  
Author(s):  
T J Miller ◽  
J R Skalski
Keyword(s):  
North Pacific ◽  
Sampling Design ◽  
Sensitive Species ◽  
Seabird Species ◽  
Probability Sampling ◽  
Complex Sampling ◽  
The North ◽  
The World ◽  
Complex Sampling Design ◽  
The North Pacific

Bycatch estimation for sensitive species is becoming increasingly important with the shift toward an ecosystem-based approach to fisheries management. Incidental mortalities for various seabird species occur on longline vessels throughout the world, including those in the North Pacific groundfish fleet. We present an approach to seabird bycatch estimation for North Pacific longline vessels using observer-collected data. Observers collect enormous amounts of data through a complex sampling design, but some information deficiencies preclude bycatch estimation using only probability sampling. Our approach combines probability sampling with model-dependent techniques to overcome these information deficiencies. The resulting bycatch estimator reflects the observer sampling design as closely as possible and minimizes reliance on untested model assumptions. We apply our estimator to black-footed albatross (Phoebastria nigripes) bycatch as an example and compare yearly estimates to those previously published. We also suggest changes in data collection that would further reduce dependence on model assumptions.

scholarly journals Natal origin of Namibian grey whale implies new distance record for in-water migration

2021 ◽  
Vol 17 (6) ◽  
pp. 20210136
Author(s):  
A. Rus Hoelzel ◽  
Fatih Sarigol ◽  
Tess Gridley ◽  
Simon H. Elwen
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Water Migration ◽  
Natal Origin ◽  
The North ◽  
Pacific Population ◽  
Conservation Implications ◽  
Grey Whale ◽  
The World ◽  
The North Pacific

We use genomics to identify the natal origin of a grey whale found in the South Atlantic, at least 20 000 km from the species core range (halfway around the world). The data indicate an origin in the North Pacific, possibly from the endangered western North Pacific population, thought to include only approximately 200 individuals. This contributes to our understanding of Atlantic sightings of this species known primarily from the North Pacific, and could have conservation implications if grey whales have the potential for essentially global dispersion. More broadly, documenting and understanding rare extreme migration events have potential implications for the understanding of how a species may be able to respond to global change.

Light Aircraft Navigation

1951 ◽  
Vol 4 (02) ◽  
pp. 167-177
Author(s):  
Michael Townsend
Keyword(s):  
South China Sea ◽  
South China ◽  
North Atlantic ◽  
North Pacific ◽  
Aleutian Islands ◽  
The North ◽  
Aircraft Navigation ◽  
The World ◽  
The North Atlantic ◽  
The North Pacific

This paper is an appreciation of the navigational problems encountered during a flight round the world in 1948, in a single-engined light aircraft. The route chosen (Fig. 2) covered nearly every type of flying weather in the world, from the perfect conditions of the Mediterranean in the summer to the severe climate of the Aleutian islands; navigation tests were provided by the overwater flights across the South China Sea (Hong Kong—Okinawa = 900 miles), the North Pacific (Chitose—Shemya = 1730 miles) and the North Atlantic.

scholarly journals The frequency and quantity of Alaskan groundfish catcher-vessel landings made with and without an observer

2011 ◽  
Vol 68 (8) ◽  
pp. 1757-1763 ◽  
Author(s):  
Craig H. Faunce ◽  
Steven J. Barbeaux
Keyword(s):  
North Pacific ◽  
Mixed Effect ◽  
Observer Effect ◽  
Linear Mixed Effect ◽  
The North ◽  
Mixed Effect Models ◽  
The World ◽  
Observer Effects ◽  
The North Pacific ◽  
Linear Mixed Effect Models

Abstract Faunce, C. H., and Barbeaux, S. J. 2011. The frequency and quantity of Alaskan groundfish catcher-vessel landings made with and without an observer. – ICES Journal of Marine Science, 68: 1757–1763. The North Pacific Groundfish Observer Programme (NPGOP) is one of the largest on-board fishery-monitoring programmes in the world, and the data are used extensively for both in- and post-season management of fisheries. Within certain limits, Alaskan fishers determine when and where to carry observers. There may be an incentive to fish differently during observed trips because (i) observed trips carry higher costs than unobserved trips, and (ii) bycatch quanta for quota deduction are estimated by applying bycatch rates from observed trips to retained catches on unobserved trips. Such differences may be manifest through the skewed deployment of observers among fisheries, i.e. a deployment effect, and through unrepresentative activities by fishers when an observer is on board, i.e. an observer effect. Despite long-standing concerns expressed over the NPGOP's 40-year history, evidence of deployment and observer effects have been based largely on anecdotal information. In 2008, database changes allowed a comparison of industry landing reports for trips with and without an observer. A deployment effect was evidenced by significant deviations from the expected landing ratios between observed and unobserved trips, and linear mixed-effect models revealed differences in the landed weight and evidence for an observer effect within two of five fisheries examined.

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