Monday, November 26, 2012

Floating Herring Weir

There were many questions this summer about the floating herring weir which was installed in the Sawpit. Most people who visit the lower Bay of Fundy are familiar with the traditional herring weir built with wooden stakes and wrapped in two layers of netting, one above the other. These passive traps rely on the fish swimming to the trap and have worked very well in years when the herring came to the surface and headed inshore at night, particularly moonless, dark nights. The design was first used by the First Nations on mud flats and was an ingenious way to capture fish.

Seining the Intruder weir, a traditional herring weir which can be seen from Swallow Tail.
The advent of floating fish pens for aquaculture of Atlantic salmon stimulated interest in developing a herring weir that would also float up and down with the tide. The netting would always be underwater and there would be moorings and anchoring lines to keep the trap in place but otherwise the principal behind how the trap fishes would be similar – heart shaped trap with the entrance indented making the fish always swim away from the entrance once inside, and a fence or leader directing fish into the trap. There have been a number of attempts using PVC pipe filled with Styrofoam and the Sawpit weir is the latest of these.
Floating herring weir in the Sawpit made from PVC piping filled with Styrofoam, anchored in several places to keep it in place.  The fence or lead extends from the shore to the mouth or entrance of the weir.
Unfortunately, this summer was yet another year when few herring came inshore at night and most of the traditional weirs were not even fitted with their nets, remaining idle. There are many theories why the herring are staying in deep water, some of which have to do with much warmer ocean temperatures. Herring prefer cooler water temperatures if the surface temperatures exceed the preference of the herring, they will retreat to deeper water where the temperature is cooler. 

Floating herring weir seen at sunrise.
Instead of herring, squid and mackerel were common inshore this summer and this resulted in multitudes of people fishing at the wharves. Not desired by the weir operator but delighting many of the visitors, many seals (harbour and grey) swam in and out of the Sawpit Weir when a school of mackerel were caught.
Grey seal.
Harbour Seal.

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