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- 2. Project goals and objectives
- Figure 1. Distribution of Atlantic halibut from NMFS bottom trawls (1963-2001)
- Review of Previous Work Federal experimental fishery in eastern Maine
- Figure 2. Atlantic halibut tag return locations (2000-2006)
- Atlantic halibut abundance surveys
- Atlantic halibut tagging studies
1. Project Title: Biological sampling, behavior and migration study of Atlantic Halibut (Hippoglossus hippoglossus) in the Gulf of MaineProject Leaders Kohl Kanwit Maine Department of Marine Resources
Maine Sea Grant/University of Maine Cooperative Extension Lead Institution Maine Department of Marine Resources Primary Partners Steve Rosen F/V Star Fisher
F/V Look Out Budget Request A total of $152,111 is requested to support one year of the proposed study. Abstract The Maine Department of Marine Resource, Maine Sea Grant, Steve Rosen and Rusty Brewer request $152,111 for a biological sampling, behavior and migration study for Atlantic halibut in the near shore Gulf of Maine. This proposal seeks to implement a fishery independent survey that will charter experienced longline halibut fishermen to collect data on the Atlantic halibut resource. Using a stratified random sampling design, the participants will record halibut catch locations, length, sex, bycatch, and environmental parameters. All halibut will be marked and released with wire tags, a sub-set of fish will receive data-storage tags and five individuals will receive satellite tags. Tagging with a combination of traditional and “smart” tags will vastly improve our understanding of this species. The proposed project will build on the results of the federal experimental fishery that occurred in eastern Maine between 2000 and 2004. This fishery provided a wealth of information on the life history of Atlantic halibut and created a partnership between commercial fishermen and fisheries scientists. This proposal is designed to continue this important research by improving our understanding of the population dynamics and biology of Atlantic halibut that will help support informed fisheries management on a recovering stock. 2. Project goals and objectives The long-term goal of this proposed study is to contribute and expand the knowledge base of Atlantic halibut population dynamics in the Gulf of Maine that will be directly used in the future assessment and management of this species. Specific objectives include: Promote a collaborative partnership between traditional halibut fishermen and researchers Provide information on regional stock abundance and distribution Estimate seasonal and individual fish movements and migration patterns Collect biological information on growth and spawning behavior Contribute information on bycatch in the bottom longline fishery 3. Value to fishery conservation and managementThe Atlantic halibut (Hippoglossus hippoglossus) is found along the continental shelf of the sub-Arctic on both sides of the North Atlantic Ocean and in parts of the Arctic Ocean. It is the largest species of flatfish inhabiting this region, reaching sizes in excess of 500 pounds (Bigelow and Schroeder, 2002). A longline hook fishery for Atlantic halibut began in the early 19th century and peaked from 1845 to 1900. The resource had commercially collapsed by the 1940s and for many years there was no directed fishery for Atlantic halibut in U.S. waters. Although the halibut resource has long been recognized as depleted in comparison to historic levels, it was not federally managed until it was identified as “overfished” by the National Marine Fisheries Service (NMFS) in 1998. As a result of this determination, NMFS included Atlantic halibut in the Multispecies Fishery Management Plan that also includes Atlantic cod, haddock and other species of commercially and recreationally important flatfish. The stock structure of Atlantic halibut in U.S. waters is not known, but results of the NMFS bottom trawl survey (1963-2001) provide limited information on the distribution of halibut in the Gulf of Maine and offshore waters (Figure 1). The highest concentrations of halibut are found in Canadian waters, on Browns Bank and off southwestern Nova Scotia. In U.S. waters, lower concentrations are found on the northern slope of Georges Bank, Stellwagen Bank and off the coast of Maine (NEFMC 1998). Due to the stock collapse of Atlantic halibut in the late 19th century, little information is available on life history, stock structure, and migratory habits in the Gulf of Maine. Studies in Canadian waters report that Atlantic halibut are demersal, living on or near the seafloor at temperatures within a few degrees of 5C (Trumble et al., 1993). Atlantic halibut are thought to spawn from February to April but spawning areas are not currently identified. According to older literature, halibut are believed to mature first as four year olds for males and six year olds for females (Bigelow and Schroeder, 2002). However, Sigourney et al. recently published a paper (2006) that identifies median maturity for males at age six and over seven for females based on limited samples from the NMFS trawl survey and two years of the experimental fishery. Figure 1. Distribution of Atlantic halibut from NMFS bottom trawls (1963-2001) 
There is currently no directed fishery for Atlantic halibut in federal waters. Landings are comprised mostly of incidental catches from bottom trawlers prosecuting other species of groundfish. Since the landing limit is one fish per trip, many halibut are sold directly to restaurants or kept for personal consumption and never recorded on Vessel Trip Reports (VTRs). However, in Maine territorial waters a remnant halibut fishery has persisted among lobstermen who traditionally set out tub trawls in the spring. In order to regulate this sentinel fishery, the state put forward regulations in 2000 to establish a minimum size limit of 36 inches, mirroring the federal rule. The state proposed additional regulations in 2002 to limit the take of halibut to four per day and a total of 50 fish per season. Two three-month seasons were defined for the coast of Maine, April-June for the western half of the state and May-July for the eastern half of the state. As a result of these regulations, state waters fishermen must also obtain an endorsement and complete a training session that reviews laws and instructs fishermen on how to keep logbooks and tag undersized fish. Fish voluntarily tagged by the state waters fishermen continue to be recaptured in Canadian waters in appreciable numbers and further research is warranted to identify if Atlantic halibut is a shared stock. A federal experimental fishery occurred annually in eastern Maine over the course of two months between 2000 and 2004. The information gathered by halibut longline fishermen through this study, dramatically increased our understanding of the Atlantic halibut population structure and life history. Prior to the experimental fishery, current information pertaining to Atlantic halibut in U.S. waters was generated through NMFS otter trawl surveys. Otter trawls capture mainly smaller halibut because larger fish are not normally susceptible to that gear type (Zwanenburg et. al. 2003). Sampling a more representative portion of the population using hooks has contributed to our knowledge on maturity stages, and age at size and weight relationships. The federal experimental fishery ended in 2004 and there is currently no other research focused on Atlantic halibut in U.S. waters. In his review of the 2004 experimental fishery application, Dr. Brodziak of the Northeast Fisheries Science Center (NEFSC) indicated that it would be especially beneficial if some data storage tags could be used: "The 2004 EFP will provide further evidence to inform US and Canadian fishery managers on whether this stock needs to be included in the set of resources jointly managed as transboundary stocks. On this point, it would be very useful to apply some modern data storage tags in future work. These tags record depth and temperature at regular intervals and could provide a wealth of information on individual fish behavior as well as habitat use and preference. For example, data storage tags are currently providing valuable data on yellowtail flounder behavior and movements. We think a similar program applied to Atlantic halibut would be a very positive cooperative research project.” Funding of this proposal would, among other things, provide the necessary resources to apply and release archival tags. On April 15, 2004 NMFS placed Atlantic halibut on a new Endangered Species Act (ESA) list called “species of special concern”. NMFS established this new category for species that the agency has concerns regarding status and threats, but for which insufficient information is available to indicate a need to the list the species under ESA. In light of this, we believe that is essential to collecting data on the abundance, distribution and movement of Atlantic halibut in the Gulf of Maine through a fishery independent survey. Atlantic Canada and the Pacific Northwest both have commercially and recreationally important halibut fisheries. The International Pacific Halibut Commission (IPHC) has regulated halibut since 1923 and has a reputation for managing one of the healthiest fisheries in North America. Collecting the information proposed in this project is an important step toward monitoring the rebuilding of the Atlantic halibut stocks in the Gulf of Maine and eventually managing a profitable and biologically sustainable fishery. In addition, the study will continue to foster a collaborative partnership between commercial fishermen, state and federal resource agencies, and academic scientists in studying this species. All partners will offer their expertise in the design and implementation stages, which will result in a practical and credible study. Review of Previous Work Federal experimental fishery in eastern Maine In light of the lack of biological information available for Atlantic halibut, the Maine Department of Marine Resources (DMR) made a request to NMFS in the spring of 2000 to conduct an experimental fishery in the eastern Gulf of Maine. DMR in conjunction with NMFS and Maine Sea Grant is currently administered five years of the Gulf of Maine Experimental Halibut Fishery between 2000 and 2004. The experiment included six participating vessels that were permitted to fish for halibut in federal waters with longline gear and sell their catch while complying with biological sampling protocols and tagging. The program collected information on 2,432 halibut since its inception in 2000 and tagged 929 of these fish. Ninety-eight tagged halibut have been recaptured to date, representing a 10.5% return rate (Figure 2). Returns have come from state waters fishermen, experimental fishery participants, groundfish trawlers, gillnetters and Canadian longliners. Twenty-seven of the returns were recaptured in the waters off Atlantic Canada. This is a significant and important finding related to the movement of Atlantic halibut in the Gulf of Maine across the international boundary with Canada. Figure 2. Atlantic halibut tag return locations (2000-2006) 
Atlantic halibut abundance surveys The National Marine Fisheries Service (NMFS) conducts routine otter trawl surveys to monitor the abundance of groundfish stocks (Grosslein, 1969; Azarovitz, 1981). This survey provides a limited historical index of Atlantic halibut abundance in the Gulf of Maine. In estimating halibut abundance from the west coast NMFS trawl surveys, the IPHC reported that trawls have the advantage of being able to cover large areas that would not be economically feasible to sample in its entirety with longlines or setlines. A disadvantage is that trawl surveys cannot sample very hard bottom that is often preferred by halibut. Also, the IPHC stated that the net trawl is selective for smaller fish in comparison to longline gear (Clark et al., 1997). This sampling bias is related to fish size and burst swimming speeds that allow large halibut to out-swim bottom trawls. Although longline surveys are very time consuming and labor intensive, this gear can be set across any bottom topography and the size selectivity can be controlled through hook size. Finally, data collected through a longline survey can be compared to the sentinel longline commercial fishery. The IPHC has relied on longline surveys and commercial catch rates by longline fishermen as the predominant method of monitoring stock abundance. The Canadian Department of Fisheries and Oceans (DFO) in Halifax, NS developed a longline survey for Atlantic halibut in 1998 to complement the standardized otter trawl surveys conducted on the Scotian Shelf (Zwanenburg and Wilson, 2000). Zwanenburg reported that the gear type and distribution of fishing effort for the otter trawl surveys were less than ideal and generated highly variable information for halibut. The longline survey was developed through collaboration between DFO and commercial halibut fishermen that, in addition to improving the knowledge base for this species, intended to promote effective working relationships between the two groups. This longline survey utilized the expertise of fishermen while allowing for the inclusion of scientific methodology. The stratified random phase of this program was designed to give an unbiased annual estimate of halibut abundance, with historical catch rates as the stratifying variable. The DFO longline survey is currently completing its eighth consecutive year and has been successful in generating a wealth of information pertaining to halibut abundance, distribution, diet, and by-catch composition as well as strengthening the partnership between industry and fisheries scientists. Atlantic halibut tagging studies Atlantic halibut movements and migrations have been the focus of several studies. Stobo et al. (1988) summarized tagging experiments conducted by the Northwest Atlantic Fisheries Organization (NAFO) in Subareas 3 and 4 between 1958 and 1973. During this time frame, a total of 1295 halibut were tagged and 285 were recaptured for an overall recovery rate of 22%. Petersen disc tags were used in all cases and the fork lengths of the fish and release locations were recorded. Over 17% of the recaptures were made after the fish had been at large for more than 5 years and one fish was caught 18 years after being released. Data from the recaptures showed a tendency for halibut released on the Scotian Shelf to move towards the northeast, while fish released on the Newfoundland Grand Bank showed no preference for movement. The Laurentian Channel did not appear to be a barrier to migration for this species. The results indicated that halibut become more sedentary as they get older, and that younger fish may range 1000 km from the original release site. Stobo et al. (1988) proposed that the limited movement by larger fish may be due to a cyclic annual migration between feeding and spawning grounds, as is suggested for Pacific halibut (H. stenolipsis). The authors recommended that, because of the extensive movement of halibut throughout most of the Canadian Northwest Atlantic, a single area encompassing the Scotian Shelf and the Grand Banks would be the most feasible management unit. Zwanenburg and Wilson (2000) reported a similar tagging effort on the Scotian Shelf, where 2000 halibut were tagged throughout the 1990’s. T-bar tags were attached by participating commercial fishermen, which has resulted in about 200 recoveries to date. Results were comparable to those reported by Stobo et al. (1988), indicating a trend in the movement of halibut towards the northeast with younger fish ranging greater distances. The IPHC has tagged and released over 427,000 Pacific halibut between 1925 and 2003 with over 46,000 reported recoveries. (Geernaert, 2003). The IPHC has predominantly used wire spaghetti tags since the 1960’s, after double tagging studies showed that they had a lower shedding rate and were more conspicuous than other designs (Kaimmer, 2000). The IPHC has recently employed pop-up satellite transmitting archival tags (PSATS) to study seasonal migration of adult halibut in the Gulf of Alaska (Loher, 2003). Twelve halibut were tagged with PSAT’s during the 2002 summer setline survey. Ten tags successfully detached from the fish and transmitted data. Most of these tagged halibut predictably moved to relatively deep water and offshore by the end of the tagging period, but two fish showed unexpected behavior by moving inshore in mid-winter. Data recovered on depth showed a tendency toward shallower waters until December and than a rapid movement toward deeper waters. 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