- Animals: Oysters
- Animal Production: animal protection and health, aquaculture, genetics
- Farm Business Management: risk management
The Ostreid Herpesvirus is a highly lethal virus and is the most imminent threat to the survival of the U.S.
Shellfish industry. One variant (OsHV-1µVar) of this virus has devastated Pacific Oyster culture
industries in Australia, Europe and New Zealand. Other commercial species of bivalves are vulnerable in
varying degrees. The U.S. variant OSHV-1 is so far only present in Tomales Bay (CA) and adjacent areas
but is only slightly less damaging. Up to 90% of juvenile oysters can be lost each year and cumulative
losses can be up to 35% through the growout stage. Although research is being conducted to develop OsHV-1 resistant strains, this research is slow and takes at least 2-3 generations to develop partial resistance and potentially millions of dollars. The three oyster companies involved in this proposal (Goose Point Oyster Co., Hog Island Oyster Co. and the Willapa Bay Fish and Oyster Co.) proposed to test a more rapid screening method to determine whether individual oyster broodstock possess some degree of resistance and thus begin to form the basis of broodstock pools to be used in an emergency situation if the virus spreads outside of Tomales
Bay. The Hog Island Oyster Co. can make immediate use of this since they have considerable losses
annually due to this disease. This method is based on using individual pair spawns, cryopreservation of
sperm and the warm Hawai`i conditions to reduce generation time. Nine families were created, then tested for resistance by outplanting half of each family in Tomales Bay to expose them to the virus. Half of each family was retained at the Hawaii hatcheries for future use in breeding. Of the nine families, one family demonstrated a very high level of resistance (87% survival) and several others varied between 40-50%. Thus,
developing resistant Pacific Oysters for commercial production can be jumped started ahead of an
emergency, rather than waiting 8-10 years for more traditional approaches to succeed.
The overall of objective is to test a new, rapid and less costly screening method to assess the
degree of disease resistance in individual broodstock oysters. These individual oysters will form
the core of a new breeding population which could essentially save the industry if a disease
outbreak occurs. We view this as an urgent and emergency measure.
Objective 1: Use individual pair spawns to produce a limited number of families to be screened
for disease resistance to OsHV-1 at Tomales Bay, CA. The parents (F0) of progeny (F1) that
show any degree of resistance will then be used in a variety of crosses to reinforce resistance.
Objective 2: Continue to develop cryogenic methods as an additional and valuable tool for
selective breeding and other uses, both practical and for research.
Training for hatchery staff, farm managers and for aquaculture students was also an important component of this work although in the original proposal we did not include this as an objective.