LAUSR

This article presents a snapshot of the diversity, maturity status, trophic structure and size of catch from a small sample of coastal mosquito net fisheries (MNF) in Mozambique. Data from these emerging fisheries are needed to understand ecological effects and management implications. However, the authors’ conclusion that ‘‘the use of mosquito nets for fishing may contribute to food insecurity, greater poverty and the loss of ecosystem functioning’’ is misleading, based on flawed assumptions, and at best premature. The discourse is built around two assumptions: (i) that ‘‘mosquito nets are entirely unselective’’, and (ii) that catching juveniles will have a substantial impact on sustainability. Here, we challenge these assumptions and highlight important social and ecological arguments for MNF that must be considered in the poverty context in which this activity occurs. The first assumption that mosquito nets are entirely unselective is demonstrably incorrect, as large fish effectively sense and avoid the slow-moving pressure wave that a dragged fine-meshed seine causes. This is the driver of the ubiquitous small-sized distribution of MNF catches. The resulting escape of large mature specimens is highly advantageous to maintaining spawning capacity, as it will conserve the BOFFFs (Big Old Fat Fecund Females, Hixon et al. 2014) and thus reduce concerns of recruitment overfishing. The second assumption is also unsubstantiated. High juvenile mortality is a distinctive characteristic of teleost life history (Fig. 1, Kolding and van Zwieten 2011). Most fish species have a very high fecundity, with extremely low natural survival of juveniles to maturity, as nearly all are ultimately food for larger fish. The common reason for protecting juveniles is the notion of growth overfishing, originating from single-species yield-per-recruit models (Beverton and Holt 1957). However, these models present a ‘‘free-lunch’’ scenario, where fish grow mathematically without accounting for the food eaten in order to grow. Yet, every kilogram gained in larger fish has a cost of * 5 kg of smaller fish or invertebrates consumed (growth efficiency * 20% as per Heymans et al. 2016). Fish breed like plants (millions of fry) but feed like carnivores (consuming mainly protein and fats). No terrestrial equivalent of this kind of animal exists (highly fecund meat eaters). As fish are adapted to high juvenile mortality (Fig. 1), and the mature BOFFFs are preserved due to escapement, MNF presents a relatively limited ecological risk compared to large-scale selective fishing of adults (Garcia et al. 2012). Single-species concepts have no relevance for multi-species MNFs such as those assessed, which take advantage of the much higher productivity and higher biomass of smallsized organisms in the aquatic biomass-size spectrum (Kolding et al. 2015). Thus, in a multi-species small-scale fishery, e.g. Mozambique, where food security is the prime concern, 5 kg of small fish are more valuable than 1 kg of large. Clearly, MNF contribute to food security, and a far more nuanced analysis is required to understand any systemlevel effects. Many small-scale fisheries have shifted fishing pattern towards more productive smaller organisms in line with the Balanced harvest principle (Garcia et al. 2012), and this is the main driver of a steady increase in total catch in many African fishery systems (Kolding et al. 2015, 2019). There is a significant risk posed by alarmist reactions and policies towards MNF, which may detrimentally