T8 AM Ecological Fate and Effects of Explosives and Related Compounds
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 337-338

(PAL-1117-689975) Examination of the potential effects of Instantaneous pressure changes on larval rainbow trout (Onchorhynchus mykiss).

Palace, V¹, Cott, P², Godard, D¹, Wautier, K¹, CLayton, D³, Wong, A⁴, Monita, D⁵, Hannah, B⁶, Morris, W⁷, Wright, D¹, ¹ Department of Fisheries and Oceans, Winnipeg, Manitoba, Canada² Department of Fisheries and Oceans, Yellowknife, NWT, Canada³ ConocoPhillips, Calgary, Alberta, Canada⁴ Encana Corporation, Calgary, Alberta, Canada⁵ Aquatics Environmental Services, Calgary, Alberta, Canada⁶ Alaska Department of Natural Resources, Fairbanks, Alaska, USA⁷ Fisheries Joint Management Committee, Inuvik, NWT, Canada

ABSTRACT- Industry and regulatory agencies in Canada acknowledge that the use of explosives under ice in fish bearing waters is potentially harmful to fish. The Department of Fisheries and Oceans, Western Arctic Area (DFO), has been closely monitoring explosives use and have been refining conditions and regulations surrounding their use. However, major gaps in our understanding of the effects of seismic activities using explosives on fish remain. For example, proven mitigation to minimize the pressure from shallow buried charges and methodologies that allow for more predictable pressures from set charges are absent. In addition, identifying the pressures that cause harm to northern over-wintering fish has become an issue of contention. Instantaneous pressure changes (IPC) from explosive charge detonation can have harmful effects on fish including damage to soft tissues from expansion beyond their elastic capacities. DFO has developed the guidelines for the use of explosives in waters such that maximum peak pressure not exceed 100kPa. This value was derived from the literature as an LD50 value for fish species in general. By virtue of being an LD50 derived value, it is not precautionary. In order to more accurately delineate IPC from explosive detonations levels that cause negative effects to fish early life stages of rainbow trout (Onchorhynchus mykiss) were subjected to a range of IPCs from explosive detonation (7 to 280kPa). Fish were held in cages suspended below ice and IPCs were monitored using seismographs and hydrophones capable of measuring a minimum of 16,000s-1 per channel. Exposed rainbow trout larvae and eggs were assessed for evidence of effects to craniofacial features, spinal curvatures, as well as soft tissues (ie. swimbladder) using microscopic and histological methods.

Key words: explosives, larval fish, pressure change, tissue damage