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FISH FACTS: What is hyperstability?

IN today’s world, management of recreational fisheries has become increasingly complex. This is due to a wide variety of reasons, some of which may not be immediately apparent to recreational fishers themselves. Over recent decades we have seen massive technological innovation in not only fishing gear and marine electronics, but also in the communications landscape due to the advent of mobile phones, the internet, social media and other online information sources. These technologies have led to rapid and dramatic changes in how recreational fishers interact with fisheries resources.

Increasing human populations have also resulted in increased destruction of fish habitat and driven significant water quality declines in inland and inshore waters. These anthropogenic impacts often affect the ability of fish populations to recruit new generations of fish into what were once prolific fisheries, leading to fish stock declines even when all the traditional fisheries management techniques we have available have been applied. The potential role of sewage/pharmaceutical contamination in the ongoing decline of bonefish populations in the Florida Keys in the USA, which I explored in a recent article on bonefish on drugs , is a case in point. This unprecedented combination of ecological (fish and environment related) and social (angler related) factors can combine to lead to a process called hyperstability.

So what is hyperstability, and why is it important?

The term hyperstability describes a process where relationships between fish catch rates and abundance of fishes become uncoupled, such that catch rates can remain higher than expected as fish abundance declines. Traditionally, recreational fisheries were thought to be largely self-regulating in many respects, based on the theory of a “sustainable negative feedback loop” in which recreational anglers would moderate their fishing effort in response to declines in fish populations. The theoretical feedback loop went along the following lines “If fish abundance decreases, anglers’ expectations for their fishing experience will not be met, and they will reduce their fishing effort, or even stop fishing altogether”. This reduction in fishing effort is then supposed to allow the fish population to recover, making it an attractive fishing target once again.

However, as explained by researchers in the USA who examined the effects of multiple challenges to stability in recreational fisheries , in the modern world this sustainable feedback loop can be broken down and undermined by various destabilizing factors which result in hyperstability. The researchers used modelling and real world data from several recreational fisheries to find that at moderate fishing effort few mechanisms were destabilizing enough to collapse a fish population, (assuming that fishing and not the environment was limiting recruitment). However, in the presence of high recreational fishing effort and the various factors that produce hyperstability, they found all bets were off, and that recreational fishing could result in fisheries collapse. Four main factors were identified in generating hyperstability. These include:

Biological factors: The main biological factors were fish behaviours which generate hyperstable catch rates (i.e. catch rates that remain high even as fish abundance declines). Examples included allowing fishing of spawning migrations or spawning aggregations which made fish particularly vulnerable to being caught, such that anglers (and fisheries managers) may not perceive or respond to declining fish abundance.

Environmental factors: The main environmental factors which encouraged hyperstability were those which influenced recruitment variability and generated significant year-to-year differences in recruitment of juvenile fish. Such examples could include wind or current variables which affect the survival of larval fish, or environmental factors such as rainfall/floods or even pollution/fish habitat destruction events, all of which can influence year class strength of fish entering a fishery.

Angler factors: The main angler-related factor in a catch and keep fishery was their behaviour in the face of catch rate declines. A population of anglers that was likely to keep fishing when catch rates approached zero was highly likely to contribute significantly to a fishery collapse. The researchers found that in fisheries where anglers are not primarily motivated by catch rates, they may continue fishing even as stocks approach collapse because they remain satisfied with other aspects of their fishing trips. Even if some or all fish are released, related issues such as mortality of released fish could still result in hyperstability problems if fishing pressure was high enough.

Technological factors: The final factor that was not explicitly covered in this particular study, but which is known to promote hyperstability, was technological improvements in fishing gear which allow anglers to increase their fishing power. These technological factors can inadvertently contribute to hyperstability related overfishing by maintaining (or even intensifying) effective fishing pressure as fish stock sizes decline. After all, it was increased commercial fishing power and technological advances in the absence of strong management which finally drove the Atlantic Cod fishery off Newfoundland into terminal decline, after 1000 years of exploitation.

From the technological side of things, there is plenty of evidence that the fishing power of the average recreational angler has increased. For example, studies have found that tournament bass anglers in the USA had become around 3 times more efficient at finding and catching fish in the 10 year period between 2005 and 2015. This threefold increase in angling efficiency was put down to “improvements in sonar systems, satellite communications, global positioning systems, fishing gears and information-sharing technologies”.

Effective fisheries management is the main solution to hyperstability, which is why fisheries independent stock assessments are increasingly important. Such management tools are more likely to pick up issues with declining fish numbers, hopefully well before catch rates begin to drop off. Maybe the way to determine if technology is artificially propping up catch rates in a fishery near you is to go out without your phone (or if boat based, your sounder/sonar and GPS too) and leave the latest tackle innovations behind. Take a handline, a few hooks and sinkers and some bait and see how you go. Food for thought, isn’t it!

For more on this issue, check out:
Focusing on what matters most: Evaluating multiple challenges to stability in
recreational fisheries


Technological innovations in the recreational fishing sector: implications for fisheries
management and policy

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