“Whether this [closing the high seas] is even worth discussing depends critically on how failed the institutions are on the HS,” says Chris Costello. “White and Costello modeled a range of scenarios for this from “perfect institutions” (in which case a HS closure makes no sense from a fishery perspective) to complete open access with many countries (in which case it does because the game theoretical outcome is to overfish significantly). I don’t know of any systematic empirical analysis of how “failed” the institutions are on the HS. My sense is that HS institutions are not great, but are probably better than they were 10 years ago.”

“Another key factor is how good the institutions are in EEZs,” Chris Costello continues. “If EEZs are not equipped to properly manage catch in a responsible manner, then this could also undermine any benefits of a HS closure.” “The concern of effort spillover hinges on institutions within EEZs,” says Costello.

Ernesto Penas-Lado holds a different view. “Like in all area-based measures, it is taken for granted that fishing pressure will be reduced, instead of simply changing area,” he says. “If HS fishing is banned, my experience tells me that many vessels would seek access to EEZs, either legally (through agreements with Coastal States) or illegally (IUU). Overall this can produce an aggravation of the overfishing already taking place in a number of EEZs around the world. The allegation by White and Costello that the measure would “reduce overall exploitation rates” is unfounded. In fact, following the declaration of 200-mile EEZs in many countries around the world, the overall fishing effort increased, not diminished, as a result, due largely to an increase in fishing pressure by the Coastal States.”

“The idea seems to be based to some extent on the belief that HS fisheries are not well managed while those in EEZs are,” Penas-Lado continues. “Again, my long experience tells me this is too often not the case at all. White & Costello say that HS fisheries are “essentially open access”. That is not true. Many of the fisheries in the HS are in fact managed, and some even very well managed. Examples are NAFO in the NW Atlantic (excellent management including enforcement), some ICCAT fisheries, the IATTC, etc. are well managed fisheries, including good enforcement. In contrast, many management systems by Coastal States within their EEZs are a complete disaster, without serious science or enforcement and with management riddled with IUU and corruption. Some countries in West Africa are the best examples.”

“The spillover effect is less than obvious to me,” says Penas-Lado. “While Sumaila et al propose a figure of a substantial 18% (not clear to me, this would need careful examination of the hypothesis, the article does not clarify all), White & Costello projections are way too optimistic and are not well founded in my view. This is certainly something that needs more careful analysis.”

Closing the HS “eliminates the RFMOs that manage the fisheries on the high seas but also with respect to harvests in national EEZs,” says Dave Fluharty. “These mechanisms are not perfect by any means but without international RFMO management the tuna ecosystem is ignored and the complications of agreement by individual states are exacerbated.” “Those proposing closure need to identify the problems with international agreements for managing highly migratory species and propose solutions for them one of which can be closure but that approach must be compared against other measures. We are talking about a very specific set of international fisheries,” Fluharty continues. “Especially with pelagic fisheries the regime must take into account variability in stock size, temporal and spatial distribution, catchability, transfer and processing and incidence of social and economic impacts.”