Management of the stalked barnacle (Pollicipes pollicipes) fishery in the Berlengas Nature Reserve (Portugal): evaluation of bag and size limit regulation measures (original) (raw)
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Scientia Marina, 2011
The stalked barnacle Pollicipes pollicipes (Gmelin, 1790) is an important shellfish resource in Portugal. Due to the social-economic importance of barnacle harvesting, a management plan aimed at achieving a controlled and sustainable activity (including temporal and spatial closures, rotational harvesting, a limited number of harvesting licenses, bag and size limits for catches and catch reporting) was implemented in 2000 at the Berlengas Nature Reserve (RNB) in central Portugal. We evaluated the bag and size limits imposed by the management plan, performing observations on harvesting activity and asking licensed harvesters and RNB staff about these measures. Both inquiries and observations suggest that licensed harvesters are not following the bag and size limits imposed. Mean amounts captured in RNB varied from 14 to 24 kg per harvester/day, but 25% of the observations corresponded to higher catches per individual than the total amount allowed (20 kg). Only half of the sampled amounts (taken in autumn 2005 and 2006) were in agreement with the size limit regulation and 50% of the total biomass comprised individuals of maximal rostro-carinal length (RC) ≥25 mm. For most harvesters, size limit is the most difficult management rule to fulfil. Both harvesters and RNB staff agree that surveillance is scarce and is a major problem of this fishing activity. In order to achieve a more sustainable use of this resource, we propose the implementation of a more effective surveillance and monitoring plan, the definition of a unique landing site, the maintenance of the bag limit (20 kg) and a reduction of the size limit (50% of total biomass comprising individuals ≥22 mm RC).
How a Sustainable Way of Collecting Bivalves Becomes Unsustainable: Case Study in Ria de Aveiro
Ria de Aveiro is a popular place where professionals and the population who lives nearby go to collect bivalves (the population does that as an economic complement). The species collected are: cockle (Cerastoderma edule), grooved razor shell (Solen marginatus), pullet carpet shell (Venerupis senegalensis) and grooved carpet shell (Ruditapes decussata). This work study is based on the observation which has been carried out for the last 10 years in the area and concludes that: The legislation applied to this activity was and is thought in order to keep the sustainability of Ria de Aveiro. In this context, the majority of the capture of these bivalves is being performed by hand or with small tools, according to the law. Although the impact is thought to be almost none (both in the environment and with the species), compared to some other capture techniques, the reality shows that these bivalves are being collected far below the legal size by adulterating the tools used in the process. ...
Fisheries Research, 2009
In this work we studied an artisanal fishery targeting mainly soles (Solea senegalensis and Solea solea) and cuttlefish (Sepia officinalis) with trammel nets. Catches of target species, bycatches and discards were studied from October 2004 until August 2005 in the west coast of Portugal. A total of 37 sampling surveys onboard commercial fishing vessels were conducted. The number and weight of individuals of all species caught were registered, as well as the amount discarded and retained by fishermen. A total of 112 species were identified: Scomber japonicus, Chelidonichthys obscura and Callioynimus lyra were the most discarded fishes, corresponding to 28% in weight and 36% in number of discards. Discards represented 22%, in weight, of the total catches, while the amount retained by fishermen for consumption or direct selling was 12%, also in weight. The overall estimate of the annual discards value due to this fishery was ca. 170 tonnes, comprising near 45 fishing vessels. Inconsistencies between the catches recorded onboard and the official landings were detected for the main target species. Some bycatches of species under recovery plans were also found.
A framework for promoting dialogue between SCRS and the Commission is proposed for advancing the application of a Harvest Control Rules consistent with the Commission's decision making framework for development and application of conservation and management measures. A provisional example is provided for northern Albacore, although the methods could be more broadly applied across the range of stocks for which quantitative stock assessments have been conducted and Kobe 2 Strategy matrices provided. RÉSUMÉ Un cadre visant à encourager le dialogue entre le SCRS et la Commission est proposé en vue de faire avancer l'application des normes de contrôle de la ponction conformément au cadre de prise de décision de la Commission pour le développement et l'application des mesures de conservation et de gestion. Un exemple est fourni à titre provisoire pour le germon du Nord, bien que les méthodes puissent être plus largement appliquées à une gamme de stocks pour lesquels des évaluations quantitatives des stocks ont été réalisées et des matrices de stratégie de Kobe 2 ont été fournies.
Hunter Reporting of Catch per Unit Effort as a Monitoring Tool in a Bushmeat-Harvesting System
Conservation Biology, 2010
Growing threats to biodiversity in the tropics mean there is an increasing need for effective monitoring that balances scientific rigor with practical feasibility. Alternatives to professional techniques are emerging that are based on the involvement of local people. Such locally based monitoring methods may be more sustainable over time, allow greater spatial coverage and quicker management decisions, lead to increased compliance, and help encourage attitude shifts toward more environmentally sustainable practices. However, few studies have yet compared the findings or cost-effectiveness of locally based methods with professional techniques or investigated the power of locally based methods to detect trends. We gathered data on bushmeat-hunting catch and effort using a professional technique (accompanying hunters on hunting trips) and two locally based methods in which data were collected by hunters (hunting camp diaries and weekly hunter interviews) in a 15-month study in Equatorial Guinea. Catch and effort results from locally based methods were strongly correlated with those of the professional technique and the spatial locations of hunting trips reported in the locally based methods accurately reflected those recorded with the professional technique. We used power simulations of catch and effort data to show that locally based methods can reliably detect meaningful levels of change (20% change with 80% power at significance level (α) = 0.05) in multispecies catch per unit effort. Locally based methods were the most cost-effective for monitoring. Hunter interviews collected catch and effort data on 240% more hunts per person hour and 94% more hunts per unit cost, spent on monitoring, than the professional technique. Our results suggest that locally based monitoring can offer an accurate, cost-effective, and sufficiently powerful method to monitor the status of natural resources. On the basis of our findings, we suggest guidelines for conservation practitioners, such as considering that socioeconomic factors drive use and peoples' incentives for monitoring. To establish such a system in Equatorial Guinea, the current lack of national and local capacity for monitoring and management must be addressed.