Marine Biology Beach Seine

beach seine netOur beautiful fall weather has offered some amazing days for outdoor explorations, especially at the beach!  As a snorkeler, I am always interested in finding out what is going on at different times of the year below the surface of the ocean.  Fish, however, are elusive, fast moving, and hard to identify as they scoot among the seaweeds.  So I was very happy to witness the workings of a beach seine collecting an array of fish that live in the nursery habitat of eel grass beds in the sheltered bays of the Gulf Islands.

Doug setting the seine net

Doug setting the seine net

Marine Biologists Doug and Jennifer Swanston came over from Vancouver for the day.  Jennifer has worked as a naturalist/interpreter for several groups, and has a BSc from UBC.  Doug Swanston has been working in the field of marine biology since the early 1980s, after graduating with his BSc from UBC.  He is involved in research as well as education.

eel grass beach seineA seine is a fishing net that hangs vertically in the water with its bottom edge held down by weights and its top edge buoyed by floats. Seine nets can be deployed from the shore as a beach seine, or from a boat.  Seine nets have been used widely in the past, all around the globe since the stone age.  Pre-European Maori deployed 1,000 meter long seine nets woven from green flax, with stone weights and light wood or gourd floats, and could require hundreds of men to haul.  American Native Indians on the Columbia River wove seine nets from spruce root fibers or wild grass, again using stones as weights. For floats they used sticks made of cedar which moved in a way which frightened the fish and helped keep them together.  Seine nets are also well documented in ancient cultures in the Mediterranean region, appearing in Egyptian tomb paintings from 3000 BC.  They are still in use today for fishing, but they also enable marine biologists to carefully collect samples of fish and other specimens for research, allowing them to be released with little disturbance.

setting the seine netDoug and Jennifer were working with a group of 24 children, from grades 4-8, who are a part of the Pender Ecological Education Community.  Doug began the day with some discussion of taxonomy and habitats; the classifications of seaweeds and grasses and the role that the different types have for different fish during the year.  The nursery habitats of the eel grass areas have been previously mapped, with help from the Seagrass Conservation Working Group, and are especially worth observing for fish populations throughout the year.  I have seen many types of small schools of fish while snorkeling, and the shallow, warmer waters protected by tall forests of the grasses with areas of sandy sea floors seem like the perfect place to hide and feed in relative safety from larger prey.

To set the seine net, Doug walked out into bay at the edge of the eel grass area and pulled along the floats of the net, leaving a rope going out of the water to the beach.  He continued to pull the net open as he waded, almost neck high, across to a large rock in the middle of the bay, and eventually came ashore with another rope.  Half the group was sent to one end of the rope, and the other half was to keep hold of the opposite side.  There were very controlled instructions, and an attentive atmosphere surrounded the kids, as movements were specific and closely monitored by Doug and Jennifer.  The group at the far end of the beach slowly pulled the rope towards the beach, while carefully walking along the beach towards the other group, who also began pulling and walking.  The idea was to make of the net a crescent shape, tucking the sides in towards the beach while leaving a gentle balloon out into the water so the fish were not startled or tangled in the net, but simply being herded in towards the beach.  As the net eventually came in closer, the excitement mounted, and Doug was wonderful at encouraging the interest but also outlining guidelines and procedures that will above all, ensure that the lives of the creatures being collected would not be harmed in any way- by being stepped on, dragged across barnacles and rocks, left out of the water, or suffering from scale damage due to too much handling.  To one concerned child he said,”this is a seine net!  If anything gets hurt, that would be insane!”

Once the net was pulled up closer to shore, the kids were encouraged to make an estimate of the number of fish rounded up.  Each child had a bucket with fresh sea water in it, and when the time came for Doug to really haul the net up, they each had the chance to scoop a fish for their own observations.  At this point, everyone was so excited- pointing and exclaiming and talking all at once, with questions and answers flying.  Silver and orange fish flashed in the vibrant green, while purple crabs clambered about and unknown creatures slithered.  Collected fish were named, shown, given seaweed to hide in, talked about, questioned, and eventually accompanied each student for a quick lunch break.  Doug was clear that the buckets had to be in a shady spot, and no hands were to be continually placed in the water, so the temperature doesn’t warm up.  Adequate oxygen levels needed to be considered, so a particularly large Whitespot Greenling was placed in a larger cooler of water.  It turned out to be a female carrying a belly full of eggs.

Doug went through the collected fish and made notes of what was found, as well as identifying to the group interesting facts about specific specimens.  Of particular interest was the bay pipefish, our local variety of sea horse, which depends on the eel grass beds entirely.  We also found a pen point gunnel, with beautiful eye stripes and a colour to match the eel grass itself.  There were lots of threespine sicklebacks, striped seaperch, pile perch, kelp perch, shiner perch, and tubesnouts, which congregate in large schools.  Doug estimated over a hundred fish were in the net, and as he pulled the net gently back out into the water to release them, he seemed quite excited that so much life was present and healthy in our local waters.

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