Humanity has a terrible track record when it comes to managing fisheries. There are many examples where over-fishing has led to the collapse of a fish population. One of the most spectacular collapses was the cod fishery in the north-west Atlantic.

Prior to the 1950s, cod had been fished off Canada for hundreds of years without any major decline in fish stocks. From the 1950s, fishing technologies improved and people got greedy.

“The decline began with the arrival of large factory stern trawlers in the late 1950s and the exploitation rate increased dramatically as these vessels were able to harvest cod offshore in winter months and at places where they were never previously caught,” (Grafton et al., 2009).

The numbers of cod caught by Canadian firms skyrocketed in the 1960s, crashed in the 1970s, recovered slightly in the 1980s and crashed to close to zero in the early 1990s.

The importance of the fishery to local economies in eastern Canada meant that their government was reluctant to take strong action to reduce fishing effort until it was too late. Right to the end, the government failed to respond as dramatically as it should have.

In 1992 they set a quota for cod catch that was more than the total amount caught the previous year. However, this quota was a foolish fantasy. By this stage the fish stock had been reduced to about one percent of what it was before the over-fishing started – there were almost no fish left that could practically be caught. So despite the quota, the government decided to impose a complete moratorium on cod fishing for two years, and since then the catch has been minimal compared to historic levels.

Ironically, the government’s delays in taking strong action were meant to benefit fishers, but this backfired terribly, resulting in huge job losses. The cod fishery had supported jobs for around 35,000 fishers and fish plant workers, although it should never have been that high, of course.

The dramatic reduction in fishing since 1992 has allowed cod stocks to recover a bit, but they remain very scarce compared to their earlier levels. In 2013 there were 10,500 tonnes of Atlantic Cod caught off eastern Canada, about 1% of the peak catch of 810,000 tonnes in 1968.

The loss of a dominant large fish from the marine ecosystem of the north-west Atlantic has had big flow-on effects, resulting in what ecologists call a “trophic cascade”, meaning that the populations of species lower down the food chain are dramatically altered.

We learn from our mistakes, if we’re sensible. In a few countries, fisheries management has improved significantly since the cod disaster. For example, New Zealand and Australia are relatively good at it compared to most countries. But globally, we are continuing to over-fish, to our own detriment. According to a 2008 report by the World Bank, “the difference between the potential and actual net economic benefits from marine fisheries is in the order of $50 billion per year – equivalent to more than half the value of the global seafood trade.” And “If fish stocks were rebuilt, the current marine catch could be achieved with approximately half of the current global fishing effort.”

Even in Australia there is more that we could do to secure our fish stocks in the long term. For example, Grafton et al. (2006) find that marine reserves where fishing is banned (Marine National Parks in our current parlance in Australia) can provide financial benefits to fishers in the long run, largely by accelerating the recovery of fish stocks in surrounding waters following an unexpected decline or “shock” (e.g. due to an environmental factor, or poor management).

If a Marine National Park is in place, fishers miss out on fishing in the reserve areas, but in the long run they are likely to be better off due to increased resilience, unless the frequency of shocks is really low.

Grafton et al. (2009) showed that a sizable no-take marine reserve in the north-west Atlantic (e.g. covering 40% of the total cod population) would have prevented the catastrophic crash in cod numbers, and would have been highly beneficial to fishers. However, the current review of zoning in our marine reserve system in Australia seems to be shaping up to reduce the planned area of Marine National Parks. I don’t think that would be in anybody’s interest.

Further reading

Grafton, R.Q., Kompas, T. and Van Ha, P. (2006). The Economic Payoffs from Marine Reserves: Resource Rents in a Stochastic Environment, The Economic Record 82(259), 469-480. Journal web site ♦ Ideas page

Grafton, R.Q., Kompas, T. and Van Ha, P. (2009). Cod today and none tomorrow: the economic value of a marine reserve, Land Economics 85(3), 454-469. Journal web site ♦ Ideas page

World Bank (2008). The Sunken Billions. The Economic Justification for Fisheries Reform. The World Bank. Washington D.C. Summary here