USPOREDNA PERFORMANSA RASTA MUŽJAKA ISTOG SPOLA I MJEŠOVITOG SPOLA NILSKE TILAPIJE (Oreochromis niloticus L.) UZGAJANIH U ZEMLJANIM RIBNJACIMA

Comparative growth performance of male monosex and mixed sex Nile tilapia (Oreochromis niloticus) was conducted in six earthen ponds each measuring 150 m2 at the Kenya Marine & Fisheries Research Institute (KMFRI), Kegati Aquaculture Research Station. Male monosex and mixed sex of O. niloticus juveniles at an average weight of 12.2 ± 0.02 g and average length of 7.6 ± 0.02 cm were collected from nursery production ponds. The male monosex juveniles were obtained by feeding newly hatched juveniles with feed dosed with 17-α-methyltestosterone hormone for a period of one month. Stocking was at 3 juvenile m-2 and feeding was carried out using 28% crude protein diet twice daily for six months at 4% body weight. Selected water quality parameters (dissolved oxygen, temperature, pH, electrical conductivity and total ammonia nitrogen) were measured weekly in situ, while sampling for weight and length measurements was conducted on a monthly basis for a period of six months. Specific Growth Rate (SGR), Feed Conversion Ratio (FCR), Condition Factor (CF) and survival rate (%) were measured at the end of six months. Data were subjected to one-way analysis of variance (ANOVA). At the end of six months, the average weight of male monosex and mixed sex fishes was 200.8 ± 0.81 g (mean ± SE) and 123.4 ± 0.76 g, respectively, while the average length of male monosex and mixed sex was 22.4 ± 0.21 cm and 18.6 ± 0.23 cm, respectively. The male monosex O. niloticus achieved significantly increased final weight and length, SGR, FCR and CF than the mixed sex O. niloticus (p 0.05). There were no significant differences in mean water quality parameters in male monosex and mixed sex ponds (p > 0.05). The male monosex fish performed better because most energy was spent on muscle and tissue development while the mixed sex fish spent most energy on reproduction activities at the expense of muscle and tissue development. Further studies should be done in other culture systems such as liner ponds, tanks, cages and raceways.Usporedna performansa rasta mužjaka istog spola u odnosu na mješoviti spol Nilske tilapije (Oreochromis niloticus) provedena je u šest zemljanih ribnjaka veličine 150 m2 u Kenijskom institutu za istraživanje mora i ribarstva (KMFRI), Akvakulturna stanica u Kegatiju. Nedozrele jedinke mužjaka istog spola i mješovitog spola O. niloticus prosječne mase 12,2 ± 0,02 g i prosječne dužine 7,6 ± 0,02 cm prikupljene su iz mladičnjaka. Nedozrele jedinke mužjaka su dobivene hranjenjem novoizleglih ličinaka s hranom doziranom hormonom 17 α-metil-testosteronom u razdoblju od mjesec dana. Nasad je proveden u gustoći od 3 mladunca / m2 i hranidbom od 28% sirovih proteina dva puta dnevno tijekom šest mjeseci na 4% tjelesne težine. Odabrani fizikalno-kemijski parametri vode (otopljen kisik, temperatura, provodljivost i ukupni amonijak) mjereni su tjedno in situ, dok su izmjere dužina i masa provedene na mjesečnoj bazi tijekom 6 mjeseci. Specifična stopa rasta (SGR), omjer konverzije hrane (FCR), kondicijski faktor (CF) i stopa preživljavanja (%) izmjereni su na kraju perioda od šest mjeseci. Podaci su analizirani jednosmjernom analizom varijance (ANOVA). Na kraju promatranog perioda od 6 mjeseci, prosječna težina mužjaka istog spola iznosila je 200,8 ± 0,81 g (prosjek ± standardna devijacija) i mješovitog spola 123,4 ± 0,76 g, a prosječna dužina mužjaka istog spola iznosila je 22,4 ± 0,21 cm i mješovitog spola 18,6 ± 0,23 cm. Mužjaci istog spola O. niloticus postigli su značajno veću konačnu težinu i dužinu, SGR, FCR i CF nego mješoviti spol (p 0,05). Nije zabilježena značajna razlika u kvaliteti mjerenih parametara u vodi ribnjaka promatranih skupina riba (p > 0,05). Mužjaci istog spola imaju bolje rezultate jer je većina energije potrošena na mišiće i razvoj tkiva, dok je mješoviti spol trošio najviše energije na reprodukcijske aktivnosti na račun mišića i razvoj tkiva. Daljnja istraživanja bi trebala biti usmjerena ka drugim sustavima uzgoja poput obloženih ribnjaka, zatvorenih bazena, kaveza i protočnih kanala

Using technology acceptance model to understand fish farmers’ intention to use black soldier fly larvae meal in Nile tilapia production in Kenya

The purpose of this study was to identify the underlying socio-psychological factors that influence pond and cage farmers’ intentions to adopt Black Soldier Fly Larvae (BSFL) in Kenya. Based on the Technology Acceptance Model (TAM), this study empirically investigated the relationship between TAM constructs, namely Perceived Ease of Use (PEOU), Perceived Usefulness (PU), Attitude towards Use (ATT), and Behavioral Intention (BI) to use BSFL. The study used a cross-sectional survey design to collect primary data from 211 randomly selected cage operators (98) and pond farmers (113) in Kenya’s Siaya, Kisumu, and Homabay Counties. A structural equation model was employed to examine hypothesized paths in the uptake of BSFL meal with the aid of SmartPLS 3. The inner model path coefficients suggested that ATT had the strongest effect on farmers’ intentions to adopt BSFL (0.411). Further, PU had a greater relative influence on intention to adopt BSFL than PEOU based on the model path coefficients of 0.319 and 0.178 respectively. This indicates that the more respondents believe BSFL is useful in their fish farm's production conditions, the more likely they are to adopt BSFL. Consequently, these findings have direct implications for policy development and the potential use of BSFL in aquaculture

Stakeholders’ perspectives on the use of black soldier fly larvae as an alternative sustainable feed ingredient in aquaculture, Kenya

The use of novel feed ingredients from aquaculture is growing globally. However, their contributions to scalable and sustainable aquafeed solutions are unclear. New ingredients for feeds are desired in the framework of sustainability and a circular economy; thus, initiatives for implementing such novel ingredients are of interest to agricultural practitioners. As research continues on the potential contribution of insect-based feeds in aquaculture in Kenya, understanding stakeholders’ perspectives about the use of black soldier fly larvae (BSFL) meal is critically important. Given that no such studies have been conducted in Kenya, the overarching goal was to quantify stakeholder perspectives on the use of BSFL meal in aquaculture. Specifically, the objectives of the study were to 1) determine stakeholders’ perceived benefits and perceived risks regarding the use of BSFL meal in aquaculture; 2) identify the important considerations when legalising BSFL meal in Kenya; and 3) determine the driving factors to promote the adoption of BSFL in fish production. Purposive sampling was used to select forty (40) experts for a Delphi study, 24 of whom responded. The Kendall’s coefficient of concordance was used to assess the experts’ consensus. The results study results suggest that there is agreement among stakeholders regarding the need to use BSFL as alternative protein ingredient in aquaculture. There was a significantly higher perception of benefits of BSFL in aquafeed than of risks, signifying a high degree of acceptance. Sanitary policy and inspection, feed safety, environmental influences and fish quality were given as the top-ranked important considerations when legalising BSFL in aquaculture. Creating and enhancing fish farmers’ awareness of the benefits of BSFL in fish production (100%) was ranked as the most important driving factor, followed by identifying pioneer farmers of safe BSFL production and their introduction as the leading farmers. Consequently, the study recommends the need for academia, government and industries to collaborate closely to develop technology on the use of BSFL in aquaculture. If further recommends that the fish farmers and insect farmers should be engaged in the process, as this might increase the acceptance of BSFL in aquaculture upon its legalisation

Determinants of fish farmers’ awareness of insect-based aquafeeds in Kenya; the case of black soldier fly larvae meal

AbstractIt is evident from scientific studies that black soldier fly larvae can replace the widely used fishmeal, which is costly and unsustainable for smallholder farmers, in aquafeeds. The purpose of this study was to evaluate the factors t influencing fish farmers’ awareness of use of black soldier fly larvae meal as an ingredient in fish feeds. The effect of farmers’ socioeconomic status and aquaculture practices on their awarenessabout black soldier fly larvae based aquafeeds was examined using a binary logit regression model. The regression analysis results revealed that fish farming experience (β = 0.327; p = 0.001), distance to feed sources (β = 0.009; p = 0.034), farmers’ income (β = −0.505; p = 0.008) and knowledge about the components of existing feed (β = 2.667; p = 0.004) significantly influenced the farmers’ awareness about black soldier fly larvae meal. The results suggest that communication and farmer education are key in improving the farmers’ awareness about novel fish feed ingredients. Therefore, there is need for both public and private institutions to improve awareness creation through local print and electronic media to enhance fish farmers’ awareness of insect-based aquafeeds

The role of indigenous knowledge in fisheries resource management for aquaculture development: A case study of the Kenyan Lake Victoria region

Abstract Indigenous knowledge is critical in the conservation of wild fish genetic resources and consequent development of fish seed for improved aquaculture production. Local fisher communities rely on aquatic resources mainly for livelihood and subsistence and have therefore come up with systems to manage these resources for sustainable use. This study aimed at identifying the role of indigenous people's knowledge in fish conservation as a way of improving aquaculture, with a specific focus on the conservation of aquaculture fish species in Kenya. Data was collected from individual fisherfolk through semi‐structured questionnaires and field observations. Pearson's chi‐square test was performed on variables that were predicted to influence indigenous knowledge. The chi‐square tests revealed a significant relationship between age and indigenous knowledge (χ2 = 15.153, p = 0.004). Results also revealed a significant relationship between an individual's years of residence in the area and indigenous knowledge (χ2 = 17.767, p = 0.003). It was found that the indigenous people use various concepts and strategies for fish conservation and fish production. From the findings of the study, it is recommended that scientists and policy actors should adopt the indigenous people's knowledge as a source of baseline information for fisheries and aquaculture research, and as additional or alternative strategies for the management of fish genetic resources