Fish provides more than 4.5 billion people with at least 15 % of their average per capita intake of animal protein. Fish’s unique nutritional properties make it also essential to the health of billions of consumers in both developed and developing countries. Fish is one of the most efficient converters of feed into high quality food and its carbon footprint is lower compared to other animal production systems. Through fish-related activities (fisheries and aquaculture but also processing and trading), fish contribute substantially to the income and therefore to the indirect food security of more than 10 % of the world population, essentially in developing and emergent countries. Yet, limited attention has been given so far to fish as a key element in food security and nutrition strategies at national level and in wider development discussions and interventions. As a result, the tremendous potential for improving food security and nutrition embodied in the strengthening of the fishery and aquaculture sectors is missed. The purpose of this paper is to make a case for a closer integration of fish into the overall debate and future policy about food security and nutrition. For this, we review the evidence from the contemporary and emerging debates and controversies around fisheries and aquaculture and we discuss them in the light of the issues debated in the wider agriculture/farming literature. The overarching question that underlies this paper is: how and to what extent will fish be able to contribute to feeding 9 billion people in 2050 and beyond?
s. World Aquaculture Society, Baton Rouge, Louisiana, p. 220. Turner, G.F. and Robinson, R.L. (2000) Reproductive biology, mating systems and parental care. In: Beveridge, M.C.M. and McAndrew, B.J. (eds) Tilapias: Biology and Exploitation. Kluwer Academic Publishers, Dordrecht/Boston/London, pp. 33–58. Twibell, R.G. and Brown, P.B. (1998) Optimal dietary protein concentration for hybrid tilapia (Oreochromis niloticus × Oreochromis aureus) fed all-plant diets. Journal of the World Aquaculture Society 29, 9–16. Uchida, R.N. and King, J.E. (1962) Tank culture of tilapia. US Fish and Wildlife Service Fisheries Bulletin 199, 21–47. Ulla Rojas, J.B. and Weerd, H.V. (1997) The growth and feed utilization of Oreochromis aureus fingerlings fed diets with various coffee pulp levels. In: Fitzsimmons, K. (ed.) Proceedings from the Fourth International Symposium on Tilapia in Aquaculture. Northeast Regional Agriculture Engineering Service, Ithaca, New York, pp. 40–49. Ungsethaphan, T. (1995) An on-farm trial to investigate feeding strategies for Nile tilapia (Oreochromis niloticus) broodfish. MSc thesis, Asian Institute of Technology, Bangkok, Thailand. United States Department of Agriculture (2004) Aquaculture Outlook. Economic Research Service, US Department of Agriculture, Washington, DC. Available at: www.ers.usda.gov Uraiwan, S. (1988) Direct and indirect responses to selection for age at first maturation of Oreochromis niloticus. In: Pullin, R.S.V., Bhukaswan, T., Tonguthai, K. and Maclean, J.L. (eds) Proceedings of the Second International Symposium on Tilapia in Aquaculture. ICLARM Conference Proceedings No. 15, Department of Fisheries, Bangkok, Thailand, and ICLARM, Manila, Philippines, pp. 295–300. van Dam, A.A., Beveridge, M.C.M., Azim, M.E. and Verdegem, M.C.J. (2002) The potential of fish production based on periphyton. Reviews in Fish Biology and Fisheries 12, 1–31. Van der Mheen-Sluijer, J. (1991) Adoption of Fish Farming: Promoting and Inhibiting Factors in Eastern Province, Zambia. Field Document GCP/INT/436/SWE.13, FAO, Harare, Zimbabwe, 41 pp. Van Dijk, P.L.M., Van den Thillart, G., Balm, P. and Wendelaar Bonga, S. (1993) The influence of gradual water acidification on the acid/base status and plasma hormone levels in carp. Journal of Fish Biology 42, 661–671. Van Ginneken, V.J.T., Van Eersel, R., Balm, P., Nieveen, M. and Van den Thillart, G. (1997) Tilapia are able to withstand long-term exposure to low environmental pH, judged by their energy status, ionic balance and plasma cortisol. Journal of Fish Biology 51, 795–806. Vannuccini, S. (2001) Global markets for tilapia. In: Subasinghe, S. and Singh, T. (eds) Tilapia: Production, Marketing and Technical Developments. Proceedings of the Tilapia 2001 International Technical and Trade Conference on Tilapia. Infofish, Kuala Lumpur, Malaysia, pp. 65–70. Varadaraj, K. (1989) Feminization of Oreochromis mossambicus by the administration of diethylstilbestrol. Aquaculture 80, 337–341. Varadaraj, K. and Pandian, T.J. (1987) Masculinization of Oreochromis mossambicus by administration of 17α-methyl5-androsten3β17β-diol through rearing water. Current Science 56, 412–413. Varadaraj, K. and Pandian, T.J. (1989) First report on production of supermale tilapia by integrating endocrine sex reversal with gynogenetic technique. Current Science 58, 434–441. Veerina, S.S., Nandeesha, M.C. and Gopal Roa, K. (1993) Status and Technology of Indian Major Carp Farming in Andra Pradesh, India. Special Publication No. 9, Asian Fishery Society. Indian Branch, Mangalore, India, 76 pp. Vera-Cruz, E.M.V. and Mair, G.C. (1994) Conditions for effective androgen sex-reversal in Oreochromis niloticus (L.). Aquaculture 122, 237–248. Verdegem, M.C. and McGinty, A.S. (1987) Effects of frequency of egg and fry removal on spawning of Tilapia nilotica in hapas. Progressive Fish Culturist 49, 129–131. Veverica, K.L., Bowman, J. and Popma, T. (2001a) Global experiment: optimization of nitrogen fertilization rate in freshwater tilapia production ponds. In: Gupta, A., McElwee, K., Burke, D., Burright, J., Cummings, X. and Egna, H. (eds) Eighteenth Annual Technical Report. Pond Dynamics/ Aquaculture CRSP, Oregon State University, Corvallis, Oregon, pp. 13–22. Veverica, K.L., Liti, D., Were, E. and Bowman, J. (2001b) Fish yield and economic benefits of tilapia/Clarias polyculture in fertilized ponds receiving commercial feeds or pelleted agricultural by-products. In: Gupta, A., McElwee, K., Burke, D., Burright, J., Cummings, X. and Egna, H. (eds) Eighteenth Annual Technical Report. Pond Dynamics/Aquaculture CRSP, Oregon State University, Corvallis, Oregon, pp. 27–29. Vincke, M.M.J. and Schmidt, U.W. (1991) Report on the Mid-term Evaluation of the Central and Northern Regions Fish Farming Projects. EEC/Government of Malawi, Zamba, Malawi, 67 pp. Viola, S. and Zohar, G. (1984) Nutrition studies with market size hybrids of tilapia (Oreochromis) in intensive culture. Bamidgeh 36, 3–15. Viola, S., Zohar, G. and Arieli, Y. (1986) Phosphorus requirements and its availability from different sources for intensive pond culture species in Israel. Part 1. Tilapia. Bamidgeh 38, 3–12. Viola, S., Arieli, Y. and Zohar, G. (1988) Animalprotein-free feeds for hybrid tilapia (Oreochromis niloticus × O. aureus) in intensive culture. Aquaculture 75, 115–125. Vromant, N., Rothuis, A.J., Cuc, N.T.T. and Ollevier, F. (1998) The effect of fish on the abundance of the rice caseworm Nymphula depunctalis (Guenée) (Lepidoptera: Pyralidae) in direct seeded, concurrent rice–fish fields. Biocontrol Science and Technology 8, 539–546. Vromant, N., Nam, C.Q. and Ollevier, F. (2002) Growth performance and use of natural food by Oreochromis niloticus (L.) in polyculture systems with Barbodes gonionotus (Bleeker) and Cyprinus carpio (L.) in intensively cultivated rice fields. Aquaculture Research 33, 969–978. Wang, J.-Q., Li, D., Dong, S., Wang, K. and Tian, X. (1998) Experimental studies on polyculture in closed shrimp ponds. 1. Intensive polyculture of Chinese shrimp (Penaeus chinensis) with tilapia hybrids. Aquaculture 163, 11–27. Wang, J.-Q., Li, D., Dong, S., Wang, K., and Tian, X. (1999) Comparative studies on cultural efficiency and profits of different polycultural systems in Penaeid shrimp ponds. Journal of Fisheries of China/Shuichan Xuebao 23, 45–52. Wang, K., Takeuchi, T. and Watanabe, T. (1985) Effect of dietary protein levels on growth of Tilapia nilotica. Bulletin of the Japanese Society for Scientific Fisheries 51, 133–140. Wang, L.-H. and Tsai, C.-L. (2000) Effects of temperature on the deformity and sex differentiation of tilapia, Oreochromis mossambicus. Journal of Experimental Zoology 286, 534–537. Wang, W.-S. and Wang, D.-H. (1997) Enhancement of the resistance of tilapia and grass carp to experimental Aeromonas hydrophila and Edwardsiella tarda infections by several polysaccharides. Comparative Immunology and Microbiology of Infectious Diseases 20, 261–270. Wang, Z-G. and Xu, B-H. (1985) Studies on the pathogenic bacteria of the ‘rotten-skin’ diseases of the Nile tilapia (Tilapia nilotica). Journal of Fisheries of China/Shuichan Xuebao 9, 217–221. Wangead, C., Greater, A. and Tansakul, R. (1988) Effects of acid water on survival and growth rate of Nile tilapia (Oreochromis niloticus). In: Pullin, R.S.V., Bhukaswan, T., Tonguthai, K. and Maclean, J.L. (eds) Proceedings of the Second International Symposium on Tilapia in Aquaculture. ICLARM Conference Proceedings No. 15, Department of Fisheries, Bangkok, Thailand, and ICLARM, Manila, Philippines, pp. 433–438. Wan Johari, W.D., Ismail, A.A., Wan Ismail, W.I. and Tahir, S.M. (1999) Transportation of Live Red Tilapia (Oreochromis niloticus) under Minimal Water Condition. Occasional Paper No. 10, Malaysian Agricultural Research and Development Institute (MARDI), Kuala Lumpur, 3 pp. Wardoyo, S.E. (1991) Effects of different salinity levels and acclimation regimes on survival, growth, and reproduction of three strains of Tilapia nilotica and a red Tilapia nilotica hybrid. PhD thesis, Auburn University, Auburn, Alabama. Wassef, E.A., Plammer, G. and Poxton, M. (1988) Protease digestion of the meals of ungerminated and germinated soybeans. Journal of Food Science and Agriculture 44, 201–214. Wassef, E.A., Sweilam, M.A. and Attalah, R.F. (2003) The use of fermented fish silage as a replacement for fish meal in Nile tilapia (Oreochromis niloticus) diets. Egyptian Journal of Nutrition and Feeds 6, 357–370. Wassermann, G.J. and Afonso, L.O.B. (2003) Sex reversal in Nile tilapia (Oreochromis niloticus Linnaeus) by androgen immersion. Aquaculture Research 34, 65–71. Watanabe, T. (1985) Importance of the study of broodstock nutrition for further development of aquaculture. In: Cowey, C.B., Mackie, A.M. and Bell, J.G. (eds) Nutrition and Feeding in Fish. Academic Press, London, pp. 395–414. Watanabe, T. and Kiron, V. (1995) Red sea bream (Pagrus major). In: Bromage, N.R. and Roberts, R.J. (eds) Broodstock Management and Egg and Larval Quality. Blackwell Science, Oxford, UK, pp. 398–413. Watanabe, T., Takeuchi, T., Murakami, A. and Ogino, C. (1980) The availability to Tilapia nilotica of phosphorus in white fish meal. Bulletin of the Japanese Society for Scientific Fisheries 46, 897–899. Watanabe, T., Arakawa, T., Kitajima, C. and Fujita, S. (1984) Effect of nutritional quality of broodstock diets on reproduction of red sea bream. Bulletin of Japanese Society for Scientific Fisheries 50, 495–501. Watanabe, T., Satoh, S. and Takeuchi, T. (1988) Availability of minerals in fish meal to fish. Asian Fisheries Science 1, 175–195. Watanabe, T., Takeuchi, T., Satoh, S. and Kiron, V. (1996) Digestible crude protein contents in various feedstuffs determined with four freshwater fish species. Fisheries Science 62, 278–282. Watanabe, W.O. and Kuo, C-M. (1985) Observations on the reproductive performance of Nile tilapia (Oreochromis niloticus) in laboratory aquaria at various salinities. Aquac
Alexis Imbert, Stéphanie Boulêtreau, Jean‐Nicolas Beisel
et al.
ABSTRACTRecreational anglers use ground baiting to attract fish and increase catch inputs organic matter that can have important effects on water quality by increasing eutrophication. However, nutrient inputs from angling bait by recreational fisheries have not yet been estimated. We quantified nutrient inputs from angling baits in small lakes supporting specialized carp, put‐and‐take, and specialized roach recreational fisheries with a 2‐year field survey of angling activity and in‐person angler questionnaires. Angling activity was highly variable among recreational fisheries and averaged 82 (±74 SD) angler‐day/ha/year in lakes with specialized carp fisheries, 145 (±80) in lakes with put‐and‐take fisheries, and 36 (±18) in lakes with specialized roach fisheries. Angling activity also differed temporally among recreational fisheries, with high angling activity in spring and summer for specialized carp and specialized roach fisheries, and in autumn and winter for put‐and‐take fisheries. The type and amount of baits used by anglers strongly differed among recreational fisheries, with specialized carp anglers using boilies (2.5 ± 1.5 SD kg/angler/day) and seeds (2.1 ± 1.9 kg/angler/day), put‐and‐take anglers using exclusively pellets (0.39 ± 0.15 kg/angler/day), and specialized roach anglers using ground baits (0.72 ± 0.36 kg/angler/day). Nutrient inputs from angling baits were highly variable among recreational fisheries and ranged from 0.5 (±0.2 SD) kg/ha/year of nitrogen and 0.1 (±0.0) kg/ha/year of phosphorus in specialized roach fisheries to 10.2 (±9.3) kg/ha/year of nitrogen and 1.6 (±1.5) kg/ha/year of phosphorus in specialized carp fisheries. Our findings revealed that ecological consequences of ground baiting differed among recreational fisheries, which should be useful for developing fishery‐specific regulations to efficiently manage ground baiting.
Md. Rabiul Awal, Md. Ashikur Rahman, Rubaiya Pervin
et al.
ABSTRACT This study focuses on inducing spawning in the vulnerable fish species Esomus danricus using pituitary gland (PG) extract. Both male and female fish received intramuscular pituitary gland injections in a 1:1 ratio. Female fish were administered doses of 4 (T1), 6 (T2), and 8 mg kg−1 (T3), while male fish received a consistent dose of 2 mg kg−1 across all treatments. Within 3–4 h of injection, the fish exhibited courtship behaviour. The average spawning rates, expressed as mean ± standard deviation, were 27.33% ± 1.77%, 49.43% ± 2.31%, and 77.67% ± 4.87% in April; 35.63% ± 2.85%, 60.67% ± 4.11%, and 87.33% ± 5.87% in May; and 37.69% ± 3.40%, 65.52% ± 4.55%, and 95.67% ± 6.09% in June for T1, T2, and T3, respectively. The latency period for spawning was observed to be 6–9 h across all treatments. The highest fertilisation rate was recorded in June at 93.53% ± 6.12% for T3, while the lowest was in April at 53.67% ± 4.60% for T1. Similarly, the highest hatching rate was detected in June at 91.27% ± 5.78% for T3, and the lowest in April at 30.33% ± 3.91% for T1. Hatching occurred within 20–24 h for all treatments, and post‐yolk sac absorption was noted within 60–72 h. This study successfully standardised breeding doses, offering promising prospects for the conservation and propagation of the native small fish species, Esomus danricus.
The current study was conducted to investigate the influences of dietary compound acidifier (CA, Formic acid (45 %), malic acid (0.3 %), Fumaric acid (0.6 %) and Succinic acid (0.6 %), Biomin Feed Additives (Shanghai) Ltd) on the growth, anti-oxidation, immunity, and intestinal health of channel catfish (Ictalurus punctatus). Six experimental diets (about 36 % crude protein and 5 % crude lipid) were prepared with graded levels of dietary CA (0 (control), 0.05 %, 0.10 %, 0.20 %, 0.40 %, and 0.80 %). A total of 648 fish with similar initial body weight (143.77 ± 0.73 g) were randomly placed into 18 tanks, with 36 fish in each tank. Fish were hand-fed to apparent satiation thrice daily for 72 days (water temperature was 25–27℃). The results showed that the WGR (weight giant rate) and SGR (specific growth rate) of channel catfish in the 0.10 % group were significantly increased compared with the control group (P < 0.05). The broken line model revealed that 0.0863 % of dietary CA was recommended for optimal SGR. The SOD (superoxide dismutase) activity and MDA (malondialdehyde) content in the serum in the 0.10 % groups were remarkably increased and decreased compared with the control group, respectively (P < 0.05). The ACP (acid phosphatase), LZM (lysozyme) activities and ALB (albumin) contents in the serum were significantly increased after supplementation of 0.10–0.40 %, 0.10–0.20 % and 0.40–0.80 % of dietary CA, respectively (P < 0.05). The AKP (alkaline phosphatase) activity in the serum in the 0.05 % and 0.10 % groups was decreased compared with other groups (P < 0.05). The GOT (glutamic oxalacetic transaminase) and GPT (glutamic pyruvic transaminase) activities in the serum notably decreased by 0.10–0.20 % and 0.05 % of dietary CA, respectively (P < 0.05). The T-CHO (total cholesterol) and HDL-C (high density lipoprotein cholesterol) contents in the serum increased by 0.80 % and 0.05 %-0.80 % of dietary CA (P < 0.05). The TG (triglyceride) content in the serum was lowest in the 0.10 % group. The expression levels of gh (growth hormone), ghr (growth hormone receptor), igf-1 (insulin-like growth factors 1), igf-2, igfbp-1 (insulin-like growth factor-binding proteins-1), igfbp-2 and igfbp-3 in the liver of the 0.10 % group were significantly higher than the control and 0.08 % groups (P < 0.05). The level of tgf-β (transforming growth factor beta), il-10 (interleukin 10), caspase3, caspase7, caspase9, occludin, zo-1 (zonula occludens-1), zo-2, claudin-12, claudin-15a, claudin-15b in the intestine of the 0.10 % group significantly increased compared with the control group (P < 0.05). Supplementation of 0.10 % dietary CA could improve the microbial diversity in the intestine of channel catfish. In conclusion, adding 0.10 % of dietary CA to the diet could improve the growth performance, anti-oxidative capacity, immunity, and intestinal health of channel catfish. Based on the SGR, the recommended optimal level of CA for channel catfish was 0.0863 %. The mechanisms regulating the growth-promoting and health-improving effects of CA on channel catfish need to be further investigated.
Francesca Moino, Alessandro Giacardi, Giovanbattista Califano
et al.
This study examines the impact of the Rural Development Program (RDP) on reducing income disparities between farms in mountainous and non-mountainous areas in Piedmont, Italy. Using Farm Accounting Data Network data from 2012–2022, the analysis focuses on cattle, sheep and goats, and fruit farms, with 562 farms (3,557 observations; 39% in mountainous areas). A pooled multivariate regression assesses income disparities excluding RDP support, RDP’s effectiveness in mitigating gaps, and the role of compensatory allowance.
Findings reveal that significant income disparities are limited to cattle farms, where mountain farms experience a net shortfall of €25,506 on average. RDP support reduces 26.56% of this gap, with compensatory allowance contributing 66.68% of the reduction. Other RDP measures account for the remaining 33.32%. However, much of the gap persists; doubling compensatory allowance payments to €206/ha would be required to eliminate the disparity.
The paper is devoted to the well-known problem of smooth structures on moment-angle manifolds. Each real or complex moment-angle manifold has an equivariant smooth structure given by an intersection of quadrics corresponding to a geometric realisation of a polytope. In 2006 F.Bosio and L.Meersseman proved that complex moment-angle manifolds of combinatorially equivalent simple polytopes are equivariantly diffeomorphic. Using arguments from calculus we derive from this result that real moment-angle manifolds of combinatorially equivalent simple polytopes are equivariantly diffeomorphic and the polytopes are diffeomorphic as manifolds with corners.
The stress‐coping ability (SCA) is one of the core aspects of fish welfare and is of vital importance for fish production in the aquaculture industry and for fish fitness in hatchery release. Environmental enrichment (EE), a method of introducing external stimuli into the husbandry environment, has been recently proposed to improve fish SCA, but the present experimental evidence is mixed, and the reasons for these discrepancies are unclear. Here, we conducted a global meta‐analysis using a data set that consists of 1786 cases from 107 studies across 42 fish species to solve this problem. Overall, we found that enriched fish had significantly higher SCA than control fish, reflected in either basal stress levels or stress responses. Meta‐regression analyses showed that specific subgroups of enrichment type, fish developmental stage, stress category, stress duration, stress place, sample tissue and indicator system showed significant positive EE effects on SCA. Multi‐model inference indicated that the indicator system, fish developmental stage, stress characteristic and enrichment mode are important drivers for the high heterogeneity among effect sizes. These results highlight the importance of introducing EE into the rearing systems, which will not only increase the welfare of aquaculture fish but also improve the ecological adaptability of released fish. The comprehensive knowledge obtained in this analysis will provide insights into fish ontogenetic plasticity and its responses to EE and have important implications for improving the production cycle in fish aquaculture and fisheries conservation.
Nile tilapia (Oreochromis niloticus), native to Africa and the Levant, is an important species for both aquaculture and capture fisheries. Despite these attributes, Nile tilapia has been negatively impacted by anthropogenic activities ranging from overfishing and habitat destruction to translocations. These human‐mediated activities have threatened the genetic evolutionary integrity of native populations of Nile tilapia and congeneric species through admixture, demographic bottlenecks and introgressive hybridization. In this context, the genetic contrast between farmed/bred strains and wild Nile tilapia populations in the major lakes of Uganda remains understudied. Understanding the genetic structure of Nile tilapia populations in the major water bodies of Uganda (lakes Victoria, Kyoga, Edward, George, Albert and Nile River) is a key resource to guide selective breeding programmes, thus minimizing the effects of maladaptation under both aquaculture and natural stocks. Although the population genetics of Nile tilapia in Uganda's major lakes have been studied, this was based on limited sampling scope, especially in the wild, and the key information on the species could have been overlooked. We fill this knowledge gap by genotyping 756 Nile tilapia individuals from multiple populations for each major water body of Uganda using a panel of 34 microsatellite loci based on the microsatellite genotyping‐by‐sequencing (SSR‐GBS) technique. The results indicate two discrete gene pools/stocks: the Edward‐George system and the Albert‐Kyoga system‐Victoria. Evidence of loss of genetic diversity and admixture of some Nile tilapia stocks was found, most likely resulting from anthropogenic perturbations. This study contributes useful information key for understanding the potential Nile tilapia broodstock sources for selective breeding programmes, aimed at improving aquaculture production in Uganda.
The rapid growth of pangasius and tilapia aquaculture has created export opportunities for Bangladesh; however, this industry is facing multiple barriers to becoming a competitive whitefish exporter in the international market. We analyzed a widely used conceptual framework and reviewed the available literature to unpack the barriers to pangasius and tilapia exports in mainstream global markets. Primary data were collected by interviewing 60 associated stakeholders to consolidate the research objectives. A meta-analysis of the literature and primary data revealed that pangasius and tilapia exporters face various internal (company and product barriers) and external (industry, market, and macroenvironment barriers) barriers. To overcome these barriers, the pangasius and tilapia industries need separate export-oriented policies and legislation to be developed by the competent authority, namely, the Department of Fisheries (DoF), which needs to provide common guidelines to meet international standards of aquaculture practices, food safety, quality, certification, and export markets. The DoF should ensure robust oversight through effective monitoring and surveillance mechanisms to implement the regulations and policies. Drawing insights from China and Vietnam’s experiences in responsible aquaculture practices, navigating export markets, and instituting aquaculture certification could provide invaluable lessons for Bangladesh. Using these lessons to overcome impediments could catalyze the flourishing of Bangladesh’s pangasius and tilapia sectors in the global whitefish market.
Fish feed is critical in aquaculture production, accounting for over 60% of operational costs, with protein being the most expensive component. Traditionally, fish meal (FM) has been the primary protein source. However, due to declining capture fisheries and high demand, FM has become scarce and costly, necessitating the search for alternative, low‐cost, and nutritionally balanced protein sources. A 180‐day feeding experiment was conducted to evaluate the effects of replacing FM with a combination of cottonseed and sunflower meal (SFM) in Nile tilapia diets on growth performance, protein digestibility, and economic returns. Freshwater shrimp meal was replaced at 25%, 50%, 75%, and 100% (diets D1, D2, D3, and D4) and compared to the control diet (D0) containing only FM. Monosex Nile tilapia fingerlings (25 ± 0.01 g) were allocated to 15 cages within an 800 m2 earthen pond. Fish on diets D0 and D1 showed superior growth performance metrics, including final mean body weight, weight gain, daily weight gain, specific growth rate, feed conversion ratio, and survival rate (p > 0.05), compared to diets D2, D3, and D4. Growth performance declined significantly with increasing levels of the plant protein mixture (p 0.05). Thus, the plant protein mixture can effectively replace FM at a 25% inclusion level in Nile tilapia diets.
Managing freshwater fisheries in warming lakes is challenging because climate change impacts anglers, fish, and their interactions.We integrated recent models of current and future lake temperatures with recreational fisheries catch data from 587 lakes in three north‐central U.S. states (Michigan, Minnesota, and Wisconsin) to evaluate how the thermal composition of recreational fisheries catch varied as a function of temperature, ice coverage, and lake morphometry.We found that warmwater catch share (WCS), defined as the proportion of fish in recreational angling catch that belonged to the warmwater thermal guild (final temperature preferendum [FTP] > 25°C), increased with average annual lake surface temperature and decreased with survey ice coverage. However, we also found that WCS decreased with increased lake area and depth. Using mid‐century (2040–2060) water temperature and ice projections while holding all other variables constant, we predicted that WCS will likely increase as the climate warms but that significant thermal heterogeneity will persist.Lakes that are large (>100 ha) and deep (>10 m) and those with cooler (<3700 annual growing degree‐days) predicted future temperatures will likely hold thermal refugia for coolwater (FTP = 19–25°C) and coldwater (FTP < 19°C) fish even as average lake temperatures rise, creating the potential for management actions to resist the shift from coolwater to warmwater fisheries. Managers of smaller and more rapidly warming lakes may want to consider strategies that accept or direct emerging warmwater fishing opportunities. We suggest that the most viable path to climate adaptation in landscapes of diverse lakes may be to resist warmwater shifts where possible and to accept or direct the rise of warmwater fishing opportunities where necessary.
L. Liverpool‐Tasie, Ayala Wineman, M. Amadi
et al.
Nigeria is Africa’s most populous country, third largest fish producer, and second largest aquaculture producer. There have been numerous studies of aquaculture and fisheries in Nigeria, but no study to date has analyzed aquaculture and capture fisheries value chains together, while giving equal weight to all value chain segments and systematically capturing information on temporal trends in value chain structure, conduct, and performance. This paper does so.We conducted a structured, qualitative, rapid reconnaissance survey of 180 actors from eight segments of the aquatic food value chain in three Nigerian states with contrasting geographies, Ebonyi, Kebbi, and Oyo.Results particularly important for future research and policy are as follows. (1) Partial vertical integration is a common feature of the organization of firms in all value chain segments, as a risk reduction strategy to overcome market imperfections and frictions. Scarcity and high cost of imported intermediate inputs is stimulating local innovation and import substitution manufacturing of feeds and fabricated items. (2) Inter-sectoral spillovers from the poultry industry have hastened the development of fish value chains, while improvements in power supply have enabled the expansion of cold storage capacity, facilitating the geographical lengthening of frozen fish value chains. (3) Rapid technological and/or institutional change is occurring in all value chain segments, including those usually viewed as traditional, such as processing and fishing. Logistics services are becoming more specialized and sophisticated, and digital communications technologies including social media play an increasingly important role in value chain coordination and marketing. (4) Increasing opportunity costs of time drive demand for convenience foods such as smoked and fried fish, which require little further preparation and can be stored at room temperature. Demand for farmed catfish is linked to growing consumption of food away from home at bars and restaurants. (5) Significant opportunities exist to improve the performance of value chains in terms of gender equity, environmental impacts, and food safety.
A. J. Danylchuk, L. Griffin, Michael J. Lawrence
et al.
Recreational angling for novel marine species and related tourism development can be important in a Blue Economy. The milkfish (Chanos chanos) is growing in popularity as a target of fly fishing‐based catch‐and‐release (C&R) recreational fisheries, largely because of their challenge to catch and powerful swimming abilities, resulting in fight times that can exceed 1 h. Anecdotal sentiments by anglers claim that milkfish can fight for long periods of time because they do not accumulate blood lactate. To test this hypothesis, we measured blood lactate and blood glucose for 21 milkfish caught by fly fishing in the remote Alphonse Group of islands, Republic of Seychelles. Fight times ranged 5–78.3 min. Blood lactate and blood glucose concentrations increased with fight times that did not exceed 60 min. Total length of milkfish was not correlated to blood lactate or blood glucose concentrations. Ours is the first study on C&R of milkfish that debunks the anecdote that milkfish can fight for long periods of time because they do not accumulate blood lactate. Our study also revealed that milkfish may begin to physiologically recover after fight times longer than 60 min. In the context of C&R, our study indicates that anglers should limit fight times to 20–30 min when possible to reduce angling‐induced physiological stress and other potential impacts (e.g., depredation) on milkfish in recreational fisheries.
Hannah Henry, Tianna Olivas, Sarah Gumbleton
et al.
Saltwater angling is a culturally significant and economically vital coastal recreational activity, particularly in the Gulf of Mexico that attracts enthusiasts worldwide and contributes significantly to the well‐being of Gulf Coast communities. However, angling can threaten ecologically important species, notably sea turtles, which are federally protected under the Endangered Species Act. In commercial fisheries, using circle hooks over traditional “J” hooks and using specific bait types can reduce sea turtle bycatch and fishing gear interactions. However, angler willingness to use these techniques is unknown. Our study aimed to assess the willingness of recreational anglers to adopt tackle modifications to support sea turtle conservation. A mixed‐mode survey was used to gather data on angler knowledge, behaviors, and attitudes toward sea turtle conservation. Generalized linear models were used to examine factors associated with angler willingness to adopt sea turtle‐friendly practices. Factors such as gender, state residency, recreational and fishing motivations, and ecological knowledge influenced angler willingness to adopt sea turtle‐friendly tackle modifications. We conclude that conservation strategies and educational outreach must be tailored to specific fishery management objectives.
Jessica A. Bolin, K. Evans, David S. Schoeman
et al.
Meat quality is of paramount importance in the fisheries and aquaculture industries, but the quality of seafood can be affected by environmental variability and change, creating uncertainties in the delivery of consistent, high‐end product. Reports from fishers operating in an Australian fishery catching broadbill swordfish (Xiphias gladius) suggest that anomalously warm waters are linked with myoliquefaction of muscle tissue. The condition affects the marketability of fish by turning the meat into a soft, mushy texture post‐mortem and is caused by infection by the myxozoan parasite Kudoa musculoliquefaciens. Here, we combine microscopy, molecular techniques and ecological modelling to explore potential environmental drivers of the prevalence and intensity of K. musculoliquefaciens in swordfish, as a first step in understanding how a warming ocean might exacerbate the risk of harvesting an infected swordfish and the resultant potential risk of myoliquefaction. We develop predictive dynamic risk surfaces on seasonal timescales, with results revealing both the likelihood of harvesting an infected swordfish and the intensity of parasite load increase during the Austral summer. The prevalence of the parasite further increases in the region dominated by the East Australian Current, when locally warm areas are atypically cool and when average monthly temperatures are more variable. These findings provide information useful in predicting the conditions under which the risk of harvesting infected swordfish might be intensified, enabling adaptation to climate change impacts and optimisation of decision‐making when fishing under risky conditions.