Page four of The Watershed Vol. 3, no. 2

Grant from The Community Foundation of Cape Cod and Gift of Free E. Coli Analyses from Envirotech, Inc., Aid Pond Studies

With the aid of a grant from the Community Foundation of Cape Cod, which OPET matched, and a gift of free fecal coliform bacteria analyses, from Envirotech, Inc., Sandwich, MA, OPET has undertaken tests for fecal coliform bacteria counts and fish studies by trapping. Further studies will we carried out throughout the year.

Fecal Coliform Bacteria
Board members Stan Hart and Birgit Rose took monthly surface samples at 6 locations of the pond. Most counts during normal weather periods were below 15/100 ml, the limit of acceptability for shellfish. Only after strong rains, counts shot up, some above 1,000. These can be attributed to runoff from roads and docks; the samplers often encountered uck, goose and swan droppings on the docks (4 sampling sites were from docks). Since a coliform count of 200 /100 ml is the safety limit for swimming, the lesson here may be not to swim in Oyster Pond right after rainstorms! Otherwise the pond seems to be doing okay in regard to coliform bacteria.

Fish Studies
With money from the grant, OPET purchased minnow traps, line and buoys. Robert Livingstone and Birgit Rose set the traps and tallied the fish. Traps were set at different depths and different locations in the pond. White perch and eel were caught in unbaited traps at 4 m depth - a good sign! Of course the most abundant catches came from the shallows, at 1 m or less: at times there were hundreds in the trap overnight, mostly killifish, some four-spine sticklebacks, occasionally silversides, and often young white perch. The perch grew about 4 cm in length in 2 months: in mid-August, their length averaged 3.5-4cm, and in mid-October it averaged 8 cm. A healthy growth rate. The largest perch trapped was 9 cm, even in bigger-mouthed minnow traps. Older perch don't seem to go into traps. This may explain the sharp decline in their number being caught by end of October. Neither do alewife go into traps. But they could be easily spotted schooling in the shallows, and especially between the weir and culvert they gathered by the thousands.

Alewives Tale (by Bob Livingstone)

Their journey has begun. They are leaving Oyster Pond now, in the autumn months, over the weir, through the culvert, into the lagoon and finally make their exodus from Trunk River into Vineyard Sound for a 3-4 year life in the ocean before returning to Oyster Pond again to repeat the cycle. Early this spring, the adult alewife spawned in the Pond. Spawning was more widespread than in other years, perhaps because of the lower salinity environment (as low as 1.2 ppt) the weir has helped bring about. By October/November, the young alewife are a good 4 inches in length and are ready to head back to sea. Bob Livingstone observed their exodus on October 9:
"I arrived at the weir at 10:40 am. Earlier in the morning, rain had come down in buckets. WQRC radio called it "car wash rain". The current was running out of the Pond. Standing on the weir and gazing down into the water I could make out numerous alewives along the banks. Suddenly hundreds and hundreds crossed back and forth over the weir. Were they getting ready to start their migration back to sea? I decided to drive to Trunk River to check. Trunk River was still flowing to the Sound. I saw no herring, but after a while the flood tide set in and pulses of salt water began traveling upriver, pushing in as far as the lagoon. It was about 11 am now, and I drove back to the weir. The current had reversed there, too, and was now flowing into the pond. Two crows were fishing from the top of the weir and 4 little green herons were perched nearby; one heron had to defend its catch from a thieving crow. The herring were now streaming over the weir by the thousands. I took a water sample: 63 F, salinity at 2.1 ppt. I returned to the weir around 2 pm. The current now ran out of the pond. The place was still alive with alewife. With my dipnet I collected a sample of 40 within seconds, measured their length and retumed them to the water. I wondered if they were exiting Trunk River now. I drove there, and I could see small pods of alewife gathering at the upstream bend. A flounder made a pass a one. The current was ebbing towards the Sound. I positioned myself on the bicycle bridge where I watched for a solid hour the alewives making their way to the Sound. Quite a sight it was!"

Epilogue: On the very same day, the Woods Hole fishing vessel Shelagh K. was reported to have sunk in the Sound with 180 ton of herring (a million or more?) in her hold! How many Oyster Pond spawnings would that be? But OPET won't be discouraged - we'll keep working to improve the pond and produce more herring yet!

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