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Last month we argued that mathematical models and fisheries science have no value for fisheries management unless their results are translated into fishing regulations. We also suggested that after stripping all the jargon out of fishing regulations, the essence that remains is really just a means of controlling fishing mortality. We said that fishing mortality could be controlled in a number of different ways, these being divided into two general classes of regulations, input controls and output controls. The discussion last month was about examples of input controls such as restrictions on the number of fishing vessels, the number of traps or hooks, the mesh size, or even the type of electronics used onboard. Input controls are really about controlling the means of fishing so that only the desired quantity of fish are caught or die as a result of fishing operations.
This month we will deal with another form of control which is very common and which, in most fisheries in the world, is used in tandem with input control regulations. The philosophy behind output controls is simple: regardless of the input control regulations already in place, you are given a specific number or tonnage of fish of a particular size, sex or species that you are allowed to land, and once you have caught your allocation you have to stop fishing. Any fish of the wrong size, species or sex must be returned to the sea. We list below the most common methods of output control:
Total allowable catch and global quota: A total allowable catch is a limit on the amount that can be removed from a single species fishery. A global quota is a limit on the amount of all species combined that can be removed from a multi-species fishery.
A limit on the total landings, or Total Allowable Catch (TAC), is the most obvious form of output control. Different approaches to enforcing this regulation exist. For low tonnage stocks (e.g. abalone or rock lobster) it is reasonable to weigh all landings at the landing point. High volume or tonnage fisheries may resort to an agreed mechanism for estimating landings, involving an element of trust between industry and government. The use of conveyer belts with scales has been implemented for industrial fisheries.
An example of the use of a global quota is provided by the South African pelagic fishery. Before 1983, this fishery was regulated by a global quota on the combined catch of anchovy, pilchard, horse mackerel, chub mackerel and round herring. The global quota allowed the species combination of the annual catch to be the same as the natural mix of species that appear in the gear. This mix of species may however imply that some species are overexploited, and others under-utilised. For this reason, the South African pelagic fishery is now regulated by a separate TAC for pilchard, and a separate TAC for anchovy. These TAC's are designed to allow full utilisation of the anchovy resource, yet to permit the rebuilding of the valuable pilchard resource, which collapsed in the 1960's.
In a mixed species fishery such as the South African pelagic fishery, the enforcement of species specific TAC's can create problems. For example, because it is not possible to target exactly on certain species, it may be necessary to dump some catches at sea, to avoid exceeding the allowance for one species, while continuing to fish for another. The wastage by dumping at sea following the implementation of species specific TAC's in a mixed species fishery should therefore be assessed, and weighed up against the benefits of this system. This would require dedicated studies on board commercial vessels.
Individual quotas: Quotas are specific tonnage's of fish that may be landed and sold by individual quota-holders. By specifying the amount that each quota-holder can catch, the race-to-fish incentive is removed. This eliminates wasteful investment in fishing gear and infrastructure designed to maintain a competitive edge in the harvesting process. As has been mentioned, this kind of investment can cause a fishery to become economically valueless. As with TAC's, the enforcement of individual quotas is expensive, and there is a clear incentive for non-compliance. The allocation of quotas is also a difficult task, since most allocation mechanisms (e.g. a quota board) are open to political manipulation.
Legally, the allocation of quota presents a number of difficulties, since in order to allocate quota, one must define what constitutes a potential quota-holder. Failure to be specific on this issue makes it very difficult to decide when and how a quota can be transferred from one party to another. Possible definitions of a potential quota holder include:
i) The owner of a fishing factory ii) The owner of a fishing vessel iii) An exporter of fish products iv) Combinations of all or some of the above.
If the quota is legally linked to ownership of a licensed fishing vessel, then this quota is transferred to the new owner of the fishing vessel upon its sale. The same would apply to other definitions of quota-holders. Allocation, transfer and definitions of ownership of quota can be enormously simplified under the proportional ITQ system discussed in the later section on access rights in fisheries. In this scheme, quota is held in the same manner as shares on the stock market, except that there is a resource rental that must be paid to the state. Therefore, quota-holding is entirely divorced from the nature of the assets held by the quota-holder, and transfer takes place under market forces.
Size restrictions: Minimum size limits are, as discussed before, set on the basis of yield-per-recruit calculations. Their intention is to maximise yield, and in some cases, to protect the spawning biomass. In fisheries where the gear catches fish smaller than the minimum size, these fish have to be returned to the sea. This is sensible if it is reasonable to assume that the fish returned to the sea have a good chance of surviving. Often this is not the case. For example, fish that are brought to the surface from great depths suffer barotrauma, a condition in which their air bladder inflates.
These fish are normally dead when they are brought on deck, and so a minimum size restriction in this kind of fishery is not effective. Fish which are alive when they are returned to the sea may nevertheless have a reduced chance of survival. This means that the intended benefit of the minimum size restriction will not be achieved in full, since there will be wastage of potential sustainable yield. These factors suggest that in considering minimum size regulations one has to make a thorough investigation of the survivorship of fish which are returned to the sea.
Sex restriction: In certain fisheries it is possible to select fish by sex as they are brought on board. If they are alive, and their chance of survival upon being returned to the sea is high, then it is sometimes beneficial to control the sex ratio in the catch, so that the catch of females is kept below a certain amount, by returning females to the sea. For example, in fisheries where there is concern that the impact on the spawning biomass is too high, and individual's survivorship upon being returned to the sea is high, the impact on the female spawning biomass can be reduced by reducing the female sex ratio in the catch.
Productive stage restriction: It is common in crustacean fisheries in which the eggs carried by in-berry females are easily visible, to establish regulations requiring fishers to return in-berry females to the water. In reality such regulations are not necessary unless the females aggregate while in-berry, making them more vulnerable to fishing.
These measures persist despite the fact that a number of field studies and simulation models have demonstrated their futility. From a population dynamics point of view it actually makes no difference when an in-berry female of a long-lived species dies. Why should the death of a female destined to go into berry tomorrow be less important than the death of female that happened to be in-berry when it was captured? In reality these measures are still very popular, mainly because they are intuitively appealing to marine biologists and to the general public, but also because they are relatively easy to enforce.
There are many other output control measures, some will say too many. Too many not because they are not important but mainly because they are often very difficult to monitor and to enforce. Our view is that global or species specific TACs are far and above the best kind of output control.