Tagged tuna graphic by Nancy Hulbirt, SOEST Illustration.

PFRP Biology Projects

Impacts of Fishing on Vulnerable Non-target Species at Seamounts

Progress Reports: FY 2012, FY 2011, FY 2010

Summary

Seamounts have extraordinary levels of endemism and exert a powerful aggregating effect on species, attracting fishes, cetaceans, seabirds and turtles. Only a few of the world’s 100,000 seamounts have been explored, leaving us with a minimal understanding of the biology of seamount organisms. Despite this, seamounts experience intensive fisheries, and interviews of commercial fishermen in Hawaii reveal frequent catches of bentho-pelagic sharks. As a result the Western Pacific Fishery Management Council and NOAA are responsible for the management of species that are potentially endemic, highly vulnerable to fishing, and so poorly understood that they cannot be assessed and for which no definitions of essential fish habitat (EFH) exist. While seamounts have been hypothesized as stepping-stones, we do not know if seamount sharks are isolated populations or if they move between seamounts and landmasses. Deep set longline fishing will be conducted at Cross Seamount to characterize the elasmobranch community. Detailed studies will be conducted for the three highest trophic level bentho-pelagic elasmobranchs, the Cooke shark (Echinorhinus cookei) the sixgill shark (Hexanchus griseus) and the sleeper shark (Somniosus pacificus). A combination of acoustic, satellite and accelerometry technologies will be used to characterize their behavior, habitat use and connectivity with other seamounts and islands. The resulting data will allow definitions of EFH and determination of appropriate management units. The proposal includes a low risk-high reward component, using established methods on new species; as well as a high risk-high reward component, that aims to develop a novel method to study these deep water animals

Objectives

1. Characterize the demersal and bentho-pelagic elasmobranchs of Cross Seamount to provide baseline data for understanding of federal management responsibilities and requirements for EFH determination.
2. Determine if the seamount sharks are resident or if they move between seamounts or islands, to better understand appropriate management units.
3. Provide unprecedented detail on movement and foraging behavior for seamount sharks via a novel technology (accelerometry). Such information may provide new means of refining fishing techniques and fishery management in order to reduce bycatch.

Methodology

Bentho-pelagic sharks will be studied at Cross Seamount using both field-tested and novel technologies. The most basic and time-tested method will be commercial longline fishing to obtain specimens. To determine behavior and habitat use, the Vemco acoustic telemetry system will be used. This system has been deployed globally, and extensively in Hawaii [Meyer 2001]. For long-distance movements, Wildlife Computers PAT tags will be used. These tags have been successfully used on many species, including a variety of sharks, and the PI has an extensive background using these tools [Weng 2005]. Because of the extensive history of using acoustic and pop-up satellite tags for this type of research these first two components of the project are almost certain to yield a large dataset on new species, and are thus low risk-high reward. To obtain detailed behavioral information, a recently developed technology will be employed, accelerometry/magnetometry [Wilson 2007]. It has never been used in a deep-water setting. Given its novelty we do not have the high assurance of success that exists with the acoustic and pop-up tag components of the project. However, it has the potential to give us an unprecedented view into the biology of these animals in the wild, and is a high risk-high reward component.

The project will occur over a three-year time frame. This will allow the dataset to span multiple years, thereby controlling for year-to-year variability. In addition, the development of the technique to successfully attach and recovery accelerometers from sharks will occur in an incremental fashion, starting in the lab, being tested in waters near Oahu, and finally being deployed at Cross Seamount.
Fishing trips will occur as part of a separate project (Hawaii Tuna Tagging Project II, HTTP-II) and will contribute significant value to this exploration. Fishing will occur aboard the vessels FV Hoku (Bruce Fukuda, captain), and FV Double D (Joe Dettling, captain). The listening array to gather data from the tagged sharks is being placed on the seamount as part of HTTP-II, funded by the NOAA Pacific Islands Fishery Science Center and PFRP. As such, the research proposed here can occur at a greatly reduced cost, while also enhancing the scientific and management return on the investment in HTTP-II. The PI has an IACUC protocol covering the proposed work approved and on file with the University of Hawaii.

Expected Outcomes

The project will yield: data useful for the definition of Essential Fish Habitat for seamount-associated sharks; possible description of new species or species extensions; behavioral data that is useful for the development of fishing methods that reduce shark by-catch.
Results will be published in the peer-reviewed literature. Descriptions of new species will be published and the type specimens archived in the Bishop museum and registered with OBIS (www.iobis.org). Management recommendations will be made where appropriate to the Western Pacific Regional Fishery Management Council, NOAA and the State of Hawaii.

Funding for this project to be available late 2009.

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References

Meyer, C.G., et al. Diet, resource partitioning and gear vulnerability of Hawaiian jacks captured in fishing tournaments. Fisheries Research, 2001. 53(2): p. 105-113.

Weng, K.C., et al. Satellite tagging and cardiac physiology reveal niche expansion in salmon sharks. Science, 2005. 310: p. 104-106.

Wilson, R.P., E.L.C. Shepard, and N. Liebsch. Prying into the intimate details of animal lives: Use of a daily diary on animals. Endangered Species Research, 2007. 3: p. 1-15.

Principal Investigator

Dr. Kevin Weng
Pelagic Fisheries Research Program (PFRP)
Joint Institute for Marine & Atmospheric Research (JIMAR)
1000 Pope Road, MSB 312
Honolulu, Hawaii 96822 USA
Phone (808) 956-4109
FAX (808) 956-4104
email: kweng@hawaii.edu

 

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