- Volume 1, Issue 1, Summer 1999 -
Summary of harbour porpoises in weirs
A new species released!
Data collected from porpoises this year
Health of the local porpoise population
Improving our methods for release
Follow the porpoises on the Web!
Proposed work next year
During the winter…
We would like to thank everyone for participating in the harbour porpoise release program this year. We thought you might like to hear about the research we conducted this summer, and so for the first time we are sending you a newsletter describing our activities.
This was the busiest year for us since 1993, with 76 porpoises recorded in Grand Manan weirs this summer. Of these, many were able to swim out on their own, and disappeared within a few days. Of the 51 porpoises we helped you seine out, we were able to release 48 successfully, giving us a success rate for this year of over 94%! This high release total includes the sweep of a group of 12 porpoises from Iron Lady (now running only second to Mystery (14 in 1993) for the largest number of porpoises we have observed in a weir at once). All of these porpoises were released from only six weirs, making this the most "concentrated" year yet. In addition to being a busy year, it was also an early year for us. We released 8 porpoises (plus a white-sided dolphin; see below) in July, and tagged three of these porpoises with satellite transmitters (see below for data from the tags). We have never put an electronic tag on a porpoise in July prior to this year. We then released another 38 porpoises in August, and to date have released two in September.
This year we added a new species to the weir release program: we released an Atlantic White-Sided dolphin from one of the weirs on July 27th. As far as we could tell this was the first time anyone had seen a dolphin in a Grand Manan weir. These animals are a bit bigger than harbour porpoises and it presented us with quite a challenge, but with the help of both the seine and pumper crews we "persuaded" the animal to leave. Dave, our diver, still complains of sore ribs and claims that while he won the battle, the dolphin definitely won the war!
We had two reappearances by previously released porpoises: one young male was released from Intruder on August 2nd, and swam into the Trojan (the floating weir) on August 20th (it swam out again that night). Another female was released from Doolittle on August 28th, only to reappear in Iron Lady and was subsequently released on August 30th. We were able to re-identify these porpoises because small coloured, numbered plastic tags (used on domestic farm animals) had been clipped to their dorsal fins. If any of you should see a porpoise with one of these tags, please let us know! This year we used green tags for males and pink tags for females (the colours change each year).
Of the 48 porpoises we released, we were able to collect sex and body size data from 31. In total, we released 12 females and 19 males. We noticed that there seemed to be more adult porpoises in weirs this year than in previous years. Typically we see a lot of juvenile porpoises (1-3 years old) but this season we saw many more mature animals. Three of the females had calves with them, and 8 of the males were likely adults (based on their body sizes). The smallest porpoise we released was a female calf that was 99 cm long. The largest animal was a 164 cm long female.
As part of a long-term study monitoring the general health of this porpoise population, we collected blood samples from 14 individuals. These blood samples undergo two types of analyses. First, part of the blood is sent immediately to Saint John, where the different types of blood cells are counted and levels of oxygen-carrying hemoglobin are measured. Later this fall the remainder of the blood, which is frozen, will be sent to the Ontario Veterinary College in Guelph, Ontario for chemistry analyses (enzyme activities, levels of different salts, proteins, and hormones, etc.). From these data we are starting to build a baseline picture of the blood values of the average wild porpoise, and we have collected enough samples to know when the values from a particular porpoise are unusual. >From the data we have obtained so far (samples from over 100 porpoises since 1993) it appears that the porpoises around Grand Manan are generally in good health, with little evidence of infections or other diseases. We also routinely measure the length and girth of each porpoise, and this gives us an indication of its body condition, or the amount of reserves (i.e. fat) that each individual carries around. This year, as in most years, all porpoises appeared extremely robust, indicating that they were in very good condition. We rarely see a "thin" porpoise in the Bay of Fundy: they all seem to be extremely fat (which, for porpoises, is a good thing).
We have also been trying to observe more closely the behaviour of porpoises during the release process so that we can try to reduce the stress they experience. The porpoises we release are filmed on videotape during the seine and while in the boat; later we can study their behaviour and breathing rates. We also record their heart rates (another indicator of stress) while they are in the boat with a monitor that is attached around their mid-section with an elastic strap (see photo above). This study is ongoing but hopefully we will have some of the data analyzed soon. We have already been able to use the results from last year's videotapes to try and reduce the porpoises' stress levels by modifying the way we interact with and handle the animals while they are in the boat.
This was a record year for satellite tag deployments: we were able to deploy 7 tags this year (our previous record was 5 in 1995). When these tags are at the surface (i.e. when the porpoise breathes) they transmit information to orbiting satellites, allowing the position of the animal to be calculated. These data are then transmitted to a ground station and we are able to access the positions via computer downloads. These tags allow us to remotely track the movements of porpoises for between 6 months and a year. We are unable to track the animals for longer periods because of limited battery life: arger batteries for longer tracks would make the tags too big for porpoises. Five of the tags allow us to collect position data, but two of them also collect and transmit information about how deep the porpoise dives between surfacings. The orpoises we put electronic tags on are listed in the table on the next page (we name each one).
Those of you with internet access can track the movements of these porpoises via the Web. Wheelock College in Massachusetts received a grant to create an educational web page about science for use in classrooms. The idea behind this is that young students will become more interested in science if they can see real data right in front of them. With their grant money, Wheelock College donates electronic tags to us and to other researchers. In exchange, we provide them with the data we collect so it can be used on their web page, called Whalenet. You can check out the travel paths of the porpoises listed above by going to this web address.
Madeleine, who has the earliest tag we have ever put out, has proved to be an extremely unusual porpoise: instead of spending the summer in the Bay of Fundy and then moving south into the Gulf of Maine in the fall, she decided to go north. As soon as she was released, she swam all the way around Nova Scotia and into the Gulf of St. Lawrence. She has now moved to the north shore of the Gulf and is travelling east again. We are all wondering where her next destination will be! We hope to be able to track Madeleine and the other porpoises into the winter months, after they all move away from Grand Manan. (A note after this newsletter was printed - Madeleine was pregnant, as determined by analysis of a blood sample taken during the release.)
We plan to continue the Harbour Porpoise Release Program next year, assisting you with the safe release of porpoises from your weirs. As most of you already know, the Harbour Porpoise Release Program is funded entirely through donations and grants from conservation organizations. We receive no federal or provincial government support. The majority of the electronic tags we deploy on porpoises have been donated to us by Whalenet, as we are only able to purchase one or two tags per year with our grant money. Each year we have to reapply to four or five organizations in order to raise enough funds to run the program for the summer. Next year we hope to raise enough additional money to purchase another small boat. The speedboat we had been using was not put into the water this year because the hull was unsafe. Fortunately one of our scientists working here on another project let us use his new boat (the new teal green one that was tied up to the North Head wharf this year) for checking weirs this summer. This boat worked out very well and we would like to purchase a similar one for the Harbour Porpoise Release Program for 2000. We plan to generate funds for this goal by writing proposals to different funding agencies over the winter.
Again, we’d like to say thank you to all of you for helping us to release almost 50 porpoises in 1999. We believe this effort is mutually beneficial to the weir fishery and to porpoise research and conservation, and plan to continue with this work for many summers to come.
Though Laurie, the Research Station managing director, lives here all year, the rest of us scatter to different places during the winter. If you have any questions, suggestions, or comments, we can all be reached through the Research Station (email: email@example.com). Several of us now spend the winter in Beaufort, North Carolina, where we go to school at the Duke University Marine Laboratory. If you ever head south during the winter, be sure to drop by.
About the Grand Manan Whale and Seabird Research Station Research Station
The Grand Manan Whale & Seabird Research Station (GMWSRS) is a non-profit research facility located in North Head. The GMWSRS was founded in 1981 by the late Dr. David Gaskin, a professor at the University of Guelph, Ontario and a pioneer of harbour porpoise research on Canada's east coast. Since 1981, the research station has conducted research on harbour porpoises, right whales, seals and seabirds in the Grand Manan Archipelago.
A GOOD WINTER AND WE'LL SEE YOU NEXT SUMMER!
Harbour Porpoise Research: 1997 | 1998
Harbour Porpoise Release Program - home page