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Advances in Marine Stock Enhancement

The Legacy of Early Stocking Programs: Stocking Doesn't Work

In the 1880's, fishery managers began to stock hatchery-reared marine organisms into the sea to increase depleted stocks. But, after 60 years of stocking eggs and yolk-sac fry, the US Bureau of Commercial fisheries (now NOAA-Fisheries) closed the last of the early marine hatcheries in the US for lack of evidence of any stocking impact on abundance of wild stocks. Stocking juveniles had never been attempted, nor was there any success in marking what was stocked to quantify survival in the wild. The technologies needed to do that simply did not exist then. After the last of the early marine hatcheries closed in Gloucester Massachusetts in 1952, the belief that stocking fish into the sea was fruitless and akin to 'chumming' the ocean with bait has persisted to this day among most fishery scientists in the US.

But some scientists, including those who would later form SCORE, realized that the attitude of their colleagues was built on failed policies of the early 20th century, before marine aquaculture and benign tagging technologies were developed. Prior to the 1980's, It was difficult, if not impossible, to apply a scientific approach to developing and evaluating stocking strategies for marine finfish. Although scientific work had finally begun on anadromous fishes in the 1970's, none of the research needed was being done to develop successful stocking strategies for marine organisms. This was mostly due to lack of interest in funding stock enhancement projects, because mangers of marine fisheries had tried it and it didn't work. Yet, all that had been tried was stocking eggs and young larvae, with no science involved to examine survival and develop effective stocking practises.

Building a Scientific Information Base: 1st Steps

Realizing the near total lack of scientific inquiry about the effects and effectiveness of marine stock enhancement, some marine scientists began to investigate basic questions about the efficacy of stocking marine organisms (i.e., that spawn in the sea) to help replenish depleted stocks. In 1989, Katsumi Tsukamoto et al. (working on red sea bream release strategies in News Bay, Japan) and Terje Svåsand and colleagues in 1990 (four articles on cod stocking in the fjords of Norway) published in peer-reviewed scientific journals the first articles written in English about the results of marine stock enhancement. The first published account by a US scientist was in 1991 (Brian F. Beal's article on the effects of size-at-release and stocking density on the fate of hatchery-reared softshell clams released into the sea).

Today, Stock Enhancement is a New Field of Scientific Inquiry

Since the early 1990's, scientific publications in this field have increased by more than an order of magnitude. A search of Cambridge Scientific Abstracts ( for journal articles published in the decades prior to 1994 revealed only 7 articles on marine stock enhancement with the words "stock enhancement", "enhancement", "stocking" or "hatchery release" in the title. Since 1994, no less than 140 more articles on marine enhancement have been published in peer-reviewed scientific journals, and some of the critical uncertainties about how to make stocking effective have been resolved. Scientific knowledge is beginning to accumulate about the fate and effects of stocking cultured marine and catadromous organisms into ocean and estuarine environments. The scientists involved in SCORE have made significant contributions to this emerging science.

>>See publications by SCORE scientists on marine stock-enhancement R&D