Base de données de recherche des TNO

Régions: Inuvialuit Settlement Region

étiquettes: contaminants, community based monitoring, marine mammals, seals

Objectif(s): To design and maintain a long-term, locally-based, monitoring program focused on ringed seals and bearded seals in the Darnley Bay region, Northwest Territories.

Description du projet: The goal of this project is to design and maintain a long-term, locally-based, monitoring program focused on ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus) in the Darnley Bay region, NWT. The goal of the first season is to conduct a pilot season from which the results will be used to determine the specific methodology moving forward. There are four main specific goals of the monitoring program that involve both ringed and bearded seals. The first and second goals are population trends and area usage and will result from the full area survey conducted at least once per season. The third and fourth goals are diet and condition, resulting from measurements made from harvested seals. Additionally, a number of tissue samples are planned in order to conduct further analyses of diet (e.g. fatty acid and/or stable isotope) and toxicology (mercury levels). Funding will determine the extent of the additional analyses. The monitoring program will be designed with two basic procedures at its onset, the focus of the pilot season. Once these have been established it may then be possible to add additional monitoring activities in future seasons. The first is a full area survey conducted at least once per season. The goal of the full area survey is to establish area usage by quantifying locations of animal concentrations. In addition, animal numbers are to be used, with caution, as indicators of local population trends. The second procedure involves measures and samples of individual seals from harvested seals. Here, the goal is to establish and quantify diet and condition of both bearded and ringed seals. 1. Seasonal Full Area Survey The aim of the full area survey is to establish numbers of seals and areas of concentration. This is best accomplished when the highest concentrations of visible seals occur and in a defined area allowing the data to be compared across seasons. Late springtime is currently thought to be the best time period for surveys. Counts would occur after pups have emerged from lairs and seals are spending their characteristically maximal amount of time hauled out of the water on the ice. The difficulty will be timing this period with accessibility for observations. The area of focus will be from the mouth of the Brock River lagoon on the east coast of Darnley Bay, around the south end of the bay and finishing just north of Bennett Point. The research team expects to be able to cover this area by boat in 2-3 days in late May to early June. During a survey all seals will be counted with binoculars at maximum distances of 300 m. distinguishing between ringed and bearded seals and between young-of-the-year and adults should be straight forward given the size difference. Distinguishing between other age classes (i.e. juveniles, sub-adults, and adults) and sexes, will not likely be possible. Counts will be opportunistic, stopping whenever animals are sited. When no seals are observed, set scans will be made at 500 m intervals, and the intervals recorded as GPS waymarks for repetition. Survey transects will be recorded by GPS waymarks. If possible, a second full area survey will be conducted in the fall from the water. The results obtained during the pilot season will be used to determine whether the additional effort is worthwhile. All survey techniques (e.g. survey boundaries; distance between observation waymarks) will be refined during the initial survey. Post season, all methodology will be reviewed and discussions with community monitors will be used to make any final adjustments. The first season will also be used to determine if there is a smaller and more accessible area of concentration (e.g. barrier Island on the mouth of the Hornaday River) that may surveyed locally on a more frequent basis (e.g. once per week mid-August to mid-September). The research team will also look into using passive acoustic monitoring techniques to monitor activity remotely (e.g. calling behavior). 2. Harvest-Based Monitoring The goal of this part of the monitoring program is to conduct morphometric measures and obtain samples from as many harvested seals as possible in order to quantify seal condition and diet. To do so, the monitors will locate themselves centrally and hunters will bring seals to them. Whether this is to be carried out in a concentrated number of days at the peak of the season or opportunistically throughout the season, is to be determined. The monitors will process seals and return them immediately to the hunter. The most likely location for the monitor to be located will be at Sandy Point just west of town, where hunters commonly bring their seals to clean. There are three basic stages to the onsite processing: (1) recording context data; (2) condition measurements; and (3) sample collection for post-processing. The context data involves: (1) time and by whom the seal was brought in; (2) time and location the seal was taken; (3) species; and (4) any extra circumstantial information noted by the hunter (e.g. seal was hauled out when taken). Condition measurements will be conducted immediately by the monitor and measurements recorded by a note keeper if available. This will include: (1) whole animal weight; (2) length (nose to extended tail flippers) and girth (circumference measured at the posterior attachment point of both foreflippers); (3) blubber thickness (measured at the sternum); (4) sex (as indicated by the presence/absence of a penile aperture); and (5) external full body check for abnormalities (e.g. hair loss). Any abnormalities detected are to be photographed. Immediately after having completed the condition measurements, samples will be taken for post-processing. The first of these is the stomach sample to infer diet. The entire stomach is to be removed and processed either immediately or stored (iced and then frozen) for processing at a later time with other stomachs. Processing will involve sorting and recording the stomach contents into identifiable species and into that which is unidentifiable. Each sorted group is to be weighed and recorded. When stomach samples are processed, the stomach will be examined for parasites or other abnormalities. If any abnormalities are detected, archival photographs will be taken. Following stomach content sampling, two teeth are to be collected in order to estimate seal age. Teeth can be pulled on-site by first breaking the lower mandible with a hammer followed by extraction with pliers (i.e. vice grips or channel-locks). If extraction without breaking the teeth is not easily accomplished on-site, half of the lower mandible should be taken (removed with knife, bolt cutters and/or hack saw) and stored in a labeled bag or processed immediately. Processing immediately is preferred and involves boiling the jaw until the teeth can be extracted. Extracted teeth will be stored in a labeled bag (seal #; species; date; location) immediately. Teeth will be sectioned and layers counted at the end of the season. The preference is to process all teeth by the monitor at the end of the season. Two experienced persons (e.g. trained monitor and the Principal Investigator) will independently count growth layers of sectioned teeth using a dissecting microscope in order to estimate seal age. Other tissues collected for post processing will include the following: (1) liver sample for toxicology and genetics; (2) fat sample for fatty acid and stable isotope analysis; and (3) tissue, vibrissae and possibly blood for corticosterone (diet stress) analysis. The optimal and minimal size of each of these samples, and the best storage techniques (e.g. alcohol, DMSO, frozen) are to be determined. If blood is taken, it will need to be spun down by centrifuge prior to storage. If there is sufficient budget allowance to have these samples processed, they are to be shipped immediately following the conclusion of the sample collection period to the appropriate laboratories for analysis. If not, samples will be stored until processed. 3. Training Training for the monitor conducting the full area survey will take place at the time of the survey in the spring. This will mainly involve counting techniques, setting up and maintaining a transect sample, and record keeping (photos and notes). Training for the collection and processing of harvested seals will involve two steps. First, if funding allows, the monitor(s) will travel to Ulukhaktok to meet and learn as much as possible. This will include, best tools and techniques for collecting samples, tooth extraction and sectioning, and how to best encourage hunters to bring their seals for processing. Second, following the Ulukhaktok meeting and at the same time as the initial training for the full area survey, the monitor(s) will work with the Principal Investigator to ensure the sample collection techniques are understood and consistently carried out. 4. Analysis The first season will be a pilot season with two main goals: (1) conducting observations etc. to ascertain what is most effective, and what methodology may need adjusting; and (2) determining what sample size is realistic. The research team expect sample sizes during seal collection to be a minimum of 20 animals and preferably 50. In terms of statistical power, a sample of 20 is marginal, but if reliably repeated, is still quantitatively valid. The focus of each analysis will be as follows. The full area survey analyses will quantify absolute numbers, absolute numbers including a correction factor (i.e. numbers not visible; from other surveys), areas of concentration (e.g. kernel densities; changes), and if possible times of peak numbers. The hunter-derived samples will focus on diet (e.g. species, biomass, change, by area/time) and condition (e.g. change in weight, length, girth, and blubber thickness over time). Both diet and condition analyses will be controlled for by age and sex. Samples taken for toxicological processing will principally focus on mercury levels for comparison with other geographic areas, other species, and over time. Samples of corticosterone will focus on diet stress over time across the different age/sex classes. Finally, fatty acid and stable isotope analyses will be compared with stomach content analyses and also analyzed for change over time and across the different age/sex classes. The core of this project involves local involvement. It is community-based monitoring of ice seals in the Paulatuk region. During the winter following the first season of data collection and after the data has been summarized, the Principal Investigator expects to travel to the community of Paulatuk in order to share the results with the community during an open Hunters and Trappers Committee meeting. The results are also to be shared with the wider Inuvialuit Settlement Region community during an Inuvialuit Game Council meeting. If possible, the timing of both presentations and discussions will occur during the same trip in order to cut down on expenses. During these meetings discussions will focus on what worked and did not work, possible changes to protocol in order to improve the process, and plans for the subsequent season. The fieldwork for this study will be conducted from May 15, 2015 to November 1, 2014.