Non-linear response of catch rates to increasing salinity levels in a small-scale fishery

Inferring abundance trends of key species from a highly developed small-scale fishery off NE Atlantic

Small-scale fisheries along the Swedish west coast are often operated by using small vessels, targeting multiple species by means of pots and gillnets. Fisheries using pots targeting shellfish such as European lobster (Homarus gammarus), and edible crab (Cancer pagurus) along the Swedish west coast have a relatively high economic value. However, gillnet fisheries targeting demersal fish are currently diminishing primarily due to depleted fish stocks and increased seal depredation. Small-scale fisheries are considered sustainable fisheries due to the use of selective gears and low energy consumption. To be able to retain and promote a sustainable small-scale fishery, there is a need to develop an economically viable fishery, where selective, seal-safe and sustainable gear is utilized. One potential way forward could be to develop a pot to be used for multiple target species traditionally caught in pots and gillnets. Since both shellfish and cod (Gadus morhua) can be caught in pots, the objective of this work was to develop a multispecies pot targeting lobster, edible crab and cod. Seven multi-species pots were developed and tested off the west coast of Sweden between 2015 and 2017. The catch rate, defined as catch per pot per day (CPUE) of lobster, edible crab and cod, was evaluated taking into regard fisheries-related variables such as pot type, bait, soak time, seal damage and abundance of species in the pot. The relative CPUE of lobster and cod was highest in larger pots with two chambers and three open entrances. The highest CPUE for lobster was 0.24 individuals per pot and the highest CPUE for cod was 0.17 individuals per pot. Pots with entrances equipped with funnels, preventing cod from escaping, also had a high cod CPUE (0.23 individuals per). The CPUE of crabs was not affected by pot type. For cod, lobster and crab, the CPUE significantly decreased with increasing soak time. Seal damage only occurred when cod were trapped in the pots and the CPUE of cod was higher in pots subjected to seal damage, indicating that seals raid pots specifically when cods are trapped inside.

The demersal fish fauna of Albatross Bay, in the eastern Gulf of Carpentaria, northern Australia, was sampled on seven cruises from August 1986 to November 1988, using a random stratified trawl survey. Four depth zones between 7 and 45 m were sampled during both day and night. The mean biomass of fish from all seven cruises was 297 kg ha−1 for days trawls and 128 kg ha−1 for night trawls. The overall mean catch rates were 922 kg h−1 for day trawls and 412 kg h−1 for night trawls. There were marked differences between cruises in both the biomass and catch rate. Approx 890 000 fish of 237 species were collected. Of these, 25 species comprised 82% of the total biomass and 74% of the overall catch rate. The dominant families were Leiognathidae, Haemulidae and Clupeidae, with Sciaenidae and Dasyatidae important at night.Leiognathus bindus was the most abundant species. Twenty-five species occurred in more than 50% of trawls, withCaranx bucculentus the most frequently caught (96% of all trawls). Thirty four species were predators on prawns; their absolute mean biomass was 50 kg ha−1 during the day and 39 kg ha−1 at night. The corresponding catch rates were 171 and 125 kg h−1. Multiple-regression analyses were used to discriminate the effects of diel, seasonal, depth and cruise patterns. Of the 31 most abundant species, 15 showed diel patterns of abundance; 11 species showed seasonal patterns of abundance; 23 species had differential depth distribution; and 13 species showed significant cruise-to-cruise variation in abundance. Cruise variations in abundance were tested against salinity, temperature, tidal exchange, plankton biomass and prawn abundances as well as periods (and lags) of total rainfall prior to sampling. Only total rainfall showed any significant correlation. Total rainfall over a period of 6 wk immediately prior to sampling showed significant positive correlations with the abundances of five species, with overall daytime catch rates, and with the suite of 34 prawn predators. Rainfall and river runoff into Albatross Bay were significantly correlated. In Albatross Bay, the complex of factors affecting fish abundances and the magnitude of between-cruise differences indicate that such tropical communities may be unpredictable and are not seasonally constant. The high catch rates in Albatross Bay relative to similar tropical areas elsewhere are discussed and attributed to the light exploitation of the Albatross Bay stocks. Other than a prawn fishery, there is no commercial trawling in Albatross Bay. Hence, the only fishing mortality is a result of by-catch from prawn trawling. The annual total of such fish by-catch is probably less than 10% of the estimated standing stock of 93 000 tonnes.

The need for the adoption of diversification strategy became germane because of challenges which impede organizational performance. This study thus examined the effect of diversification on organizational performance of selected manufacturing industries so in south west Nigeria. Some studies of strategic study have investigated on the effect of diversification on organizational performance in manufacturing industries in Nigeria but have come up with inconclusive findings which create a gap that this study wants to fill. The specific objectives of the study are to examine the effect of related diversification on organizational performance and investigate the effect of unrelated diversification on organizational performance in manufacturing industry. Ex-post facto research design was used for the study. The population consists of employees of 22 manufacturing industries listed in Nigerian Exchange Group between 2011-2020 dealing in Food and Beverages, Breweries, Health care/Pharmaceutical and Conglomerates. The sample size comprises eight manufacturing industries with 750 employee’s selected using stratified sampling technique and selected according to 50% proportion of original sample size. Data were drawn from primary and secondary sources. Descriptive statistics was used to explain the respondent’s characteristics and inferential statistics was used to analyze data collected. Findings revealed that related diversification have significant effect on organizational performance F (4, 745) = 11.988, p < 0.01, R= 0.651, R2 = 0.424, and adjusted R2 = 0.419). Unrelated diversification however have significant but negative effect on organizational performance F (4, 745) = 11.982, p < 0.05, R = -0.466, R2 = 0.217, and adjusted R2 = 0.208). The study concluded that related diversification increase organizational performance while unrelated diversif

Informed population monitoring efforts are essential for sound management of harvested species, and adaptive strategies that provide detailed information to monitoring efforts often require data inputs from complimentary sources. Movement ecology information is seldom directly incorporated into population monitoring or adaptive harvest management strategies, yet can provide valuable information on species distributions, emigration and immigration rates, and aid in determining optimal population monitoring timing. The Rocky Mountain Population (RMP) of Sandhill Cranes is a harvested population subject to a stringent adaptive harvest management framework and an annual aerial survey to estimate population abundance, but movements of Sandhill Cranes during survey windows, and subsequent changes to harvest quotas based on their movement and distribution have not been investigated. We used seven years of GPS tracking data to estimate state-specific emigration and immigration rates, using a Bayesian multi-state capture-recapture model, among states within the RMP distribution to understand how seasonal crane movements may influence optimal aerial survey timing. We then leveraged these transition probabilities in conjunction with aerial survey count data to model how changes in aerial survey timing and movement-informed crane distribution would influence the current RMP Sandhill Crane adaptive harvest management model resulting in estimated changes to harvest allocation among states based on Sandhill Crane movement. We found that Sandhill Crane emigration from northern states began to increase the week of the aerial survey in late September, and continued to increase as autumn migration progressed into October. As expected, immigration to southern states began as emigration from northern states increased. Importantly, little movement among states occurred prior to the current aerial survey design timing. Overall, we found that current survey timing and shortly thereafter (∼1 week) did not greatly influence estimates of Sandhill Crane distribution, and did not greatly influence the harvest reallocation to each state until mid to late October (range of −42–+52 tag allocation change), much later than the current survey design would allow. Using GPS locations, we found that optimal population monitoring efforts could be improved to account for both detection and seasonal movements, while minimally influencing current adaptive harvest management strategies to stakeholders. Linking movement ecology with population monitoring efforts and subsequently adaptive harvest management strategies yields insightful information that can be beneficial for conservation planning, decision-making, and optimal species management of a migratory bird.

By-catch and target species taken in 25 consecutive nights of research trawling off Duyfken Point (Weipa) in the north-eastern Gulf of Carpentaria during October–November 1995 were counted and weighed. The 24 most abundant species (by numbers per hour) caught in at least 34 of the 36 trawls, plus 2 less abundant penaeids that occurred in all trawls, were used in the analyses. To extrapolate trends in catch over the whole Gulf fishery over the same time, the prawn catch rates of the research trawls and of the commercial fishery in the same and other areas around the Gulf were compared. Catch rates for all species combined were dominated by the high abundance of Leiognathus splendens over the 25 nights. Plots of catch rates for individual species indicated some lunar periodicity in the patterns of abundance for many species. Ten species, Gerres filamentosus (P=0.012), Johnius amblycephalus (P=0.012), Leiognathus moretoniensis (P<0.001), L. splendens (P=0.007), Metapenaeus ensis (P<0.001), Penaeus esculentus (P=0.007), Sardinella albella (P<0.001), Sillago sihama (P=0.005), Torquigener whitleyi (P<0.001), Trachypenaeus spp. (P<0.001) had strong significant differences in mean catch rates between lunar phases, but the patterns differed among groups of species. The most common pattern was a distinct peak during the first-quarter moon (Sardinella albella, G. filamentosus, J. amblycephalus and L. splendens); next most common pattern was a distinct last-quarter peak (Torquigener whitleyi, L. moretoniensis and P. esculentus). The commercial penaeid Metapenaeus ensis had first-quarter and full-moon peaks, while Trachypenaeus spp. showed new- and full-moon peaks. Data obtained from the commercial fleet for endeavour prawns (Metapenaeus endeavouri and M. ensis) and tiger prawns (P. esculentus and P. semisulcatus) at the same time and area clearly showed the same patterns as in the research sampling. Endeavour prawns had a significant full-moon peak (P<0.001), and tiger prawns had a last-quarter peak (P<0.001), although the latter was not significant in the research sampling. The prawn catch rates from different areas of the Gulf showed significant differences with moon phase: P<0.001 for endeavour and tiger prawns at North Groote; P<0.001 for endeavour prawns and P=0.028 for tiger prawns at East Vanderlins; P<0.015 for endeavour prawns at West Mornington, although the peak catch rates did not occur at the same moon phase as in Weipa. The results of this study suggest that some by-catch species may need to be excluded from monitoring programmes where no account of moon phase is possible. The corollary is that the majority of by-catch species studied showed no significant changes in catch rates with moon phase and would therefore be ideal species for any sampling programme that cannot exclude the effect of moon phase.

Tropical small-scale fisheries are typical for providing complex multivariate data, due to their diversity in fishing techniques and highly diverse species composition. In this paper we used for the first time a supervised Self-Organizing Map (xyf-SOM), to recognize and understand the internal heterogeneity of a tropical marine small-scale fishery, using as model the fishery fleet of San Pedro port, Tabasco, Mexico. We used multivariate data from commercial logbooks, including the following four factors: fish species (47), gear types (bottom longline, vertical line+shark longline and vertical line), season (cold, warm), and inter-annual variation (2007–2012). The size of the xyf-SOM, a fundamental characteristic to improve its predictive quality, was optimized for the minimum distance between objects and the maximum prediction rate. The xyf-SOM successfully classified individual fishing trips in relation to the four factors included in the model. Prediction percentages were high (80–100%) for bottom longline and vertical line + shark longline, but lower prediction values were obtained for vertical line (51–74%) fishery. A confusion matrix indicated that classification errors occurred within the same fishing gear. Prediction rates were validated by generating confidence interval using bootstrap. The xyf-SOM showed that not all the fishing trips were targeting the most abundant species and the catch rates were not symmetrically distributed around the mean. Also, the species composition is not homogeneous among fishing trips. Despite the complexity of the data, the xyf-SOM proved to be an excellent tool to identify trends in complex scenarios, emphasizing the diverse and complex patterns that characterize tropical small scale-fishery fleets.

This paper illustrates the opportunity for conservation offered by linking traditional agroecological knowledge and advances in adaptive management theory and practice. Drawing on examples from the Banawa-Marawola region of Central Sulawesi, Indonesia, a suite of traditional resource management practices premised on principles of adaptive management are identified and assessed, including: (1) resource management practices and regulations that are associated with the dynamics of complex systems; (2) procedural, planning and decision-making processes that foster learning; (3) sanctions and taboos that act as social mechanisms for the management and conservation of natural resources; and (4) ceremonies and social interactions that promote cultural internalization of the various practices, procedures and mechanisms. In addition, an emerging socio-political movement in the Banawa-Marawola region is explored. Premised on the strengthening of traditional rights and practices, the nascent Kamalise movement potentially provides the socio-political, institutional and organizational context needed to link traditional agroecological knowledge and adaptive management with broader conservation goals. Based on this analysis, two opportunities to enhance conservation in the region are identified: first, maintaining traditional agroecological systems and the associated adaptive resource management strategies used by local groups, and second, building upon the Kamalise movement to forge conservation alliances among communities, non-government and government organizations in which locally-evolved adaptive resource management strategies can be effectively applied. Both opportunities to combine traditional knowledge, adaptive management and conservation, however, are linked to the development aspirations of traditional groups: self-determination, acquisition of land rights and controlling the impacts of changes in livelihood.

This chapter examined the implementation of the Voluntary Guidelines for Securing Sustainable Small-Scale Fisheries (SSF Guidelines) which were endorsed by FAO member states in 2014, in the Bangladesh small-scale fisheries context with particular focus on disaster risks and climate change related guidelines (Para. 9). Given that small-scale coastal fisheries in Bangladesh are subjected to multifaceted vulnerabilities due to extreme events and disasters, they provide an important case to study the potential implementation process of disaster risks and climate change related rules of the SSF Guidelines. The Bangladesh government is yet to take any decision regarding implementation of the SSF Guidelines. Reference to small-scale fisheries is largely absent in current ideologies, perceptions, and policies targeting disaster risks and climate change discourse in Bangladesh, although small-scale fishers are among the most climate-vulnerable population. Responses from relevant government agencies, fishers’ organizations, and NGOs are also inadequate in addressing the concerns of small-scale fisheries. This study identified priorities and potential entry points for implementation of the Guidelines in Bangladesh. It calls for the state to recognize that climate change induced disasters have intense but different impacts on small-scale fishing people than on other professional groups. Further, it is argued that effective and full consultation with fishing communities is needed, and that the government should incorporate fishers’ adaptation strategies against disaster risk and climate change impacts in existing climate change adaptation policy.

While considering important juvenile fish habitats individually, both seagrass and saltmarsh are often highly connected with other subtidal and intertidal habitats. As a result, juvenile fishes and crustaceans may utilize multiple habitats across tidal, diel, or seasonal cycles in a manner that makes interhabitat proximity an important driver of fish distribution and community composition. In this context, we examined the importance of seagrass (Zostera marina and Halodule wrightii) and saltmarsh (Spartina alterniflora) habitat characteristics in driving fish and crustacean catch rates and community composition in a temperate, polyhaline-euhaline, estuary. We found that habitats with highly connected seagrass and saltmarsh vegetation exhibited higher average catch rates of many recreationally and commercially valuable fish and crustacean species, as well as overall nekton catch rates and Shannon diversity (H), than habitats composed of either seagrass or saltmarsh habitat alone. Nekton-habitat associations varied temporally, showing strong seasonal trends which were potentially indicative of temporal shifts in relative habitat value. Catch rates of numerous recreationally and commercially targeted species were correlated with patch-scale variables, particularly seagrass canopy height, water temperature, and depth; however, regression analysis indicated that habitat type was more powerful in predicting overall nekton catch rates and Shannon diversity (H). We conclude that emergent properties (i.e., those operating at 10–100s m) are important drivers of nekton distributions among and within habitats. Considering the spatial and temporal scales at which humans are encroaching on estuarine ecosystems, our findings highlight the need for investigating organism-habitat associations at expanded spatial scales, as well as the need to adopt fishery and coastal management plans that consider habitat characteristics at multiple spatial scales to account for interhabitat connectivity.

Widespread development and shifts from rural to urban areas within the Wildland-Urban Interface (WUI) has increased fire risks to local populations, as well as introduced complex and long-term costs and benefits to communities. We use an interdisciplinary approach to investigate how trends in fire characteristics influence adaptive management and economies in the Intermountain Western US (IMW). Specifically, we analyze area burned and fire frequency in the IMW over time, how fires in urban or rural settings influence local economies and whether fire trends and economic impacts influence managers’ perspectives and adaptive decision-making. Our analyses showed some increasing fire trends at multiple levels. Using a non-parametric event study model, we evaluated the effects of fire events in rural and urban areas on county-level private industry employment, finding short- and long-term positive effects of fire on employment at several scales and some short-term negative effects for specific sectors. Through interviewing 20 fire managers, we found that most recognize increasing fire trends and that there are both positive and negative economic effects of fire. We also established that many of the participants are implementing adaptive fire management strategies and we identified key challenges to mitigating increasing fire risk in the IMW.

Alternative error distribution models for standardization of catch rates of non-target species from a pelagic longline fishery: billfish species in the Venezuelan tuna longline fishery

Increased interest in biomass harvesting for bioenergetic applications has raised questions regarding the potential ecological consequences on forest biodiversity. Here we evaluate the initial changes in the abundance, species richness and community composition of rove (Staphylinidae) and ground beetles (Carabidae), immediately following 1) stem-only harvesting (SOH), in which logging debris (i.e., tree tops and branches) are retained on site, and 2) whole-tree harvesting (WTH), in which stems, tops and branches are removed in mature balsam fir stands in Quebec, Canada. Beetles were collected throughout the summer of 2011, one year following harvesting, using pitfall traps. Overall catch rates were greater in uncut forest (Control) than either stem-only or whole-tree harvested sites. Catch rates in WTH were greater than SOH sites. Uncut stands were characterized primarily by five species: Atheta capsularis, Atheta klagesi, Atheta strigosula, Tachinus fumipennis/frigidus complex (Staphylinidae) and to a lesser extent to Pterostichus punctatissimus (Carabidae). Increased catch rates in WTH sites, where post-harvest biomass was less, were attributable to increased catches of rove beetles Pseudopsis subulata, Quedius labradorensis and to a lesser extent Gabrius brevipennis. We were able to characterize differences in beetle assemblages between harvested and non-harvested plots as well as differences between whole tree (WTH) and stem only (SOH) harvested sites where logging residues had been removed or left following harvest. However, the overall assemblage response was largely a recapitulation of the responses of several abundant species.

Reviewing the performance of adaptive forest management strategies with robustness analysis

Trends in small-scale artisanal fishing of sea cucumbers in Oceania