Effects of climate change on oceanic fisheries in the tropical Pacific: implications for economic development and food security

The four species of tuna that underpin oceanic fisheries in the tropical Pacific (skipjack, yellowfin, bigeye and albacore tuna) deliver great economic and social benefits to Pacific Island countries and territories (PICTs). Domestic tuna fleets and local fish processing operations contribute 3–20 % to gross domestic product in four PICTs and licence fees from foreign fleets provide an average of 3–40 % of government revenue for seven PICTs. More than 12,000 people are employed in tuna processing facilities and on tuna fishing vessels. Fish is a cornerstone of food security for many PICTs and provides 50–90 % of dietary animal protein in rural areas. Several PICTs have plans to (1) increase the benefits they receive from oceanic fisheries by increasing the amount of tuna processed locally, and (2) allocate more tuna for the food security of their rapidly growing populations. The projected effects of climate change on the distribution of tuna in the tropical Pacific Ocean, due to increases in sea surface temperature, changes in velocity of major currents and decreases in nutrient supply to the photic zone from greater stratification, are likely to affect these plans. PICTs in the east of the region with a high dependence on licence fees for government revenue are expected to receive more revenue as tuna catches increase in their exclusive economic zones. On the other hand, countries in the west may encounter problems securing enough fish for their canneries as tuna are redistributed progressively to the east. Changes in the distribution of tuna will also affect the proportions of national tuna catches required for food security. We present priority adaptations to reduce the threats to oceanic fisheries posed by climate change and to capitalise on opportunities.     

Values,climate change,and implications for adaptation: Evidence from two communities in Labrador,Canada

Local material and symbolic values have to date remained underrepresented in climate change research and policy and this gap is particularly salient in places that have been identified as at significant risk from climate change. In such places, the dominant approach to understanding the effects of climate change has been centred on vulnerability; it has highlighted the social determinants of vulnerability and the differential and uneven distribution of effects. This approach cannot, however, illuminate the diverse and nuanced meanings people attach to specific aspects of their way of life, how the changing climate might affect these, and what this implies for adaptation. To address this gap, this empirical study uses the concept of values, defined as trans-situational conceptions of the desirable that give meaning to behaviour and events, and influence perception and interpretation of situations and events. We develop a set of values from 53 qualitative interviews in two remote communities in subarctic easternmost Canada. It draws on these values to frame how effects of climate change, specifically intangible and subjective effects, are felt, and how responses to them are imagined by those affected. The article argues that values are crucial in shaping perception of climate impacts and adaptation to them. Distinct values, such as tradition, freedom, harmony, safety, and unity shape different interpretations and meaning of impacts, and lead to distinct views on how to adapt to these. Conflicting and competing values can act as barriers to adaptation. The findings imply that adaptation research and policy need to address values explicitly if efforts for planned adaptation are to be perceived as legitimate and effective by those affected by the changing climate.     

The effects of spatial targeting of fishing effort on the distribution of the Norway lobster,Nephrops norvegicus,on the Farn Deeps grounds,northeast England

Nephrops norvegicus is an essentially sedentary species of lobster that forms the basis of valuable fisheries in the northwest Atlantic and western Mediterranean. Fishers exploiting a sedentary stock are likely to visit the most profitable (highest catch rate) areas first. Such spatial targeting of fishing effort is likely to have important consequences for stock monitoring and assessment. We used underwater television surveys of Nephrops burrow densities on the Farn Deeps grounds, northeast England, to describe changes in abundance and distribution between the beginning and end of a winter fishing season. Above a threshold of c. 0.6 burrows m^–2, overwinter depletion increased with burrow density, consistent with fishing effort being targeted at the highest densities. A simple simulation model showed that this pattern of mortality is an expected consequence of spatially targeted fishing behaviour. The model also predicted that there is decreased spatial variability in density after fishing. An overall decrease in variability was not evident from the survey data, but geostatistical analysis indicated that there was “flattening” of the density profile along a north‐south axis, consistent with the dominant direction of commercial trawling. We concluded that Nephrops fishers are able to find and exploit the highest densities of their target species. A potential consequence is that catch per unit effort (CPUE) data used to monitor trends in this stock potentially could mask declines in stock abundance. CPUE might be more effective if analysed at finer spatial scales, but this is not currently possible. In the absence of these fine scale commercial data, fishery‐independent surveys (e.g., underwater television) are an important source of information on trends in stock abundance.     

Scleractinian settlement patterns to natural cleared reef substrata and artificial settlement panels on an Indonesian coral reef

Recruitment is a key factor driving the population dynamics of scleractinian corals, but despite its importance, we still have a poor understanding of recruitment processes in the Coral triangle region, which contains the most biodiverse marine ecosystems in the world. This study aimed to compare settlement rates to artificial settlement panels with cleared areas of natural reef in order to assess whether panels are a suitable indicator of natural coral settlement rates. We recorded coral settlement rates to panels made of two different materials (concrete and terracotta), attached to the reef at two different orientations (vertical and horizontal), and compared these settlement rates to those on cleared areas of natural reef positioned on vertical reef walls, over a 12 month period. We examined settlement rates at four sites in the Wakatobi National Marine Park, south-east Sulawesi, Indonesia; two reefs were light-limited, highly sedimented sites with low coral cover (<10%) and two had moderate coral cover (approx. 40%) and lower sedimentation rates. Panels were directly attached to the reef at 6–7 m depth. The number of coral spat per tile ranged from 0 to 34 and no significant differences were reported between the settlement rates to cleared natural reef areas and settlement panels. Significantly higher numbers of spat settled on the cryptic (back) side of the panels, while no significant difference was found between settlement rates to the different panel materials, or between the different orientations or any combination of these two factors. There is, however, a significant difference in the settlement rates between sites, for both settlement panels and permanent cleared areas, with higher settlement rates at the sites with higher live coral cover. We conclude that both concrete and terracotta panels yield similar settlement rates, and orientation makes no difference to settlement rates when panels are directly attached to the reef. Our results demonstrate that artificial substrata provide comparable settlement rate data to natural substrata and therefore are suitable for monitoring coral settlement rates in the future.     

How do you grade peperites?

A spectacular, graded peperite of volcanic origin from the Palaeogene Mull Lava Field of NW Scotland, the Carraig Mhór Bed (CMB), consists of a basal facies of pale, sub-horizontally-aligned, fluidal-shaped clasts of hydrothermally-altered basalt set in a brown, complexly-laminated, silt- to clay-grade, host siliciclastic sediment. The basal facies of the CMB grades upwards over an interval of ∼ 10 m into an upper facies dominated by smaller and more angular clasts of identical composition, set in a subordinate proportion of the same sediment matrix. The distinctive textural characteristics of the CMB, together with its remarkably uniform grading motif, may be explained in terms of the mingling of basaltic magma and fluidised siliciclastic sediment, resulting in the ductile fragmentation of magma, and production of the fluidal clasts which dominate the basal facies. Cooling of the system led to limited brittle fragmentation, yielding the finer-grained, sediment-poor upper facies of the CMB. During cooling, the larger fluidal-shaped clasts settled to the base of the unit, through the saturated sediment, producing the vertical (stratigraphic) grading now preserved. Grading occurred, essentially, in situ during peperite formation and cannot be attributed to remobilisation, mass flow or pyroclastic phenomena.