Is bigger really gooder?
08 March 2016
As headline stories go, last month's 'blue cod fillets in the fridge' piece got the sabres rattling more than most. Filtering the noise out, three lines of opinion seemed most relevant and worthy of further comment.
The first two, a New Zealander's right to enjoy a fresh caught dinner on board a vessel, and, the many ambiguous statements offered by the Ministry of Primary Industry guidelines, have been covered in detail by this media channel and others.
For me, it's the third thread of discussion which offers the most scope for deeper thought.
The mechanisms by which sensitive populations, such as the Marlborough Sounds blue cod fishery and others are managed seems to have missed public scrutiny.
In New Zealand, when a fish species is deemed under unsustainable pressure, we respond in two ways. Reducing bag limits and increasing the legal size of the species in questions.
I don't generally have issues with reduced bag limits, provided the reduction is applied evenly across all the stakeholders as a percentage. That is, if the recreational limit on a certain species is ten and it is dropped to eight, the same 20% reduction should be applied to the commercial take.
However, the constant increasing of the legal take size does warrant more thought.
My observation, through years of private and charter fishing, is that as the legal fish size increases, so does the fishing pressure in terms of the total number of fish captured and released to fill an ice bin with takeable fish.
Surely this isn't a surprise. As much as media organisations like to extoll the virtues of fishing for sport rather than the pantry, the majority of fishermen still cling to the need to take home a good catch to justify their investment in time and money on the water. And they have every right to. Fishing for the table benefits society in many ways beyond savings at the supermarket.
We also know that taking a larger average fish from a population can cause irreversible damage to the population's gene pool. Although it may not have happened yet it is theoretically possible to remove a species' capacity to grow over a certain size by literally eating all the fish which carry genes for larger growth. It is primarily for this reason that I have long encouraged the release of larger fish. Even if these big fish are past prime breeding age, if they are still capable of contributing to the gene pool they should be left to do so.
If the inevitable outcome of an increased legal fish size is more baited hooks in the water for a longer time (increased fishing pressure), and possible damage to the species gene pool, shouldn't we be looking at alternative management tools?
To that end, if an angler keeps the first seven smaller snapper he or she catches and then stops fishing isn't that a better outcome the catching 30 to take home seven medium to large-sized fish prime breeders?
We also fail to recognize exponentially higher natural mortality rate of small fish compared to medium sized fish, which are less likely to fall victim to predation.
On the topic of fish mortality, it may be worth looking more closely at our fishing techniques as a management tool. If we accept that fish survive catch and release more successfully if not gut hooked why not legislate for less invasive circle hook and lure techniques, making them mandatory?
Anyway, hopefully this gets you thinking.