Handling of The Environmental Drainage System In Jembrana District, Bali Province

The rapid growth of the urban population should be followed by the provision of basic infrastructure and facilities inadequate residential areas. One of them is the facilities and infrastructure for the environmental drainage system in residential areas to be free from standing water, especially during the rainy season. In Jembrana Regency, especially in Negara city and its surroundings, there are fourteen inundation points spread over 3 (three) districts. Drainage treatment is carried out by ranking priority scales based on inundation parameters. The parameters are inundation of height, length, frequency, and also the loss parameters due to inundation of economic facilities, public facilities, transportation facilities, housing, and casualties. With limited funds available, detailed planning is carried out on three inundation points with the highest priority score. The analysis shows that three inundation points receive priority for handling, namely Baler Bale Agung village’s environmental drainage system, Dauh Waru village, and environmental drainage Loloan Timur village. The drainage construction system uses an open channel with a U-ditch type and a box culvert with freecast concrete’s quality value of K-350.

Investigation and Development of Post-Season Modelling of Arrow Squid in the Snares and Auckland Islands

<p>Squid fisheries require a different management approach to most fish species which are much longer living. Most squid live for around one year, spawn and then die. The result of this is an entirely new stock each year with little or no relationship of stock sizes between the years. Hence, it is difficult to set appropriate catch limits prior to the season. Currently, there is nothing set up for modelling the New Zealand squid fishery in-season or post-season. In-season management would allow for adjustments of catch limits during a season. Post-season management would provide information on how much the stock was exploited during a season (described as the escapement). I have produced an integrated model using ADMB (Automatic Differentiation Model Builder) (Fournier et al., 2011) which models length frequency data, CPUE (Catch Per Unit Effort) indices and catch weights from a season. It calculates escapement which indicates how much the fishery is currently being exploited. In running the model against data from four area and year combinations, I found the escapement calculation to be stable. The results suggest this modelling approach could be used with the current data collected for post-season modelling of the fishery. I am less confident about in-season modelling with the current data collected. The integrated model fits quite poorly to the CPUE data, suggesting some discrepancy either between the data or the assumptions made of them. Sampling from a greater number of tows is recommended to improve the length frequency data and this may also improve the ability of the model to fit both to these and the CPUE.</p>

Investigation and Development of Post-Season Modelling of Arrow Squid in the Snares and Auckland Islands

<p>Squid fisheries require a different management approach to most fish species which are much longer living. Most squid live for around one year, spawn and then die. The result of this is an entirely new stock each year with little or no relationship of stock sizes between the years. Hence, it is difficult to set appropriate catch limits prior to the season. Currently, there is nothing set up for modelling the New Zealand squid fishery in-season or post-season. In-season management would allow for adjustments of catch limits during a season. Post-season management would provide information on how much the stock was exploited during a season (described as the escapement). I have produced an integrated model using ADMB (Automatic Differentiation Model Builder) (Fournier et al., 2011) which models length frequency data, CPUE (Catch Per Unit Effort) indices and catch weights from a season. It calculates escapement which indicates how much the fishery is currently being exploited. In running the model against data from four area and year combinations, I found the escapement calculation to be stable. The results suggest this modelling approach could be used with the current data collected for post-season modelling of the fishery. I am less confident about in-season modelling with the current data collected. The integrated model fits quite poorly to the CPUE data, suggesting some discrepancy either between the data or the assumptions made of them. Sampling from a greater number of tows is recommended to improve the length frequency data and this may also improve the ability of the model to fit both to these and the CPUE.</p>

Population parameters of several groupers (Famili Serranidae) in Labuan Bajo waters, East Nusa Tenggara

Labuan Bajo has a fertile aquatic ecosystem, one of them is the coral reef ecosystem. This condition happened because of the supply of nutrients that are carried through Indonesia Through Flow and the local upwelling phenomena. Various species of reef fish of various sizes have been caught in Labuan Bajo waters. In general, the type of reef fish that dominates is grouper fish catch by using handline fishing gear. Furthermore, there is damage that occurs in the coastal ecosystem causes changes in ecological functions and disrupted ecosystem benefits. In addition, pressure from overuse did not provide opportunities for resources to carry out recovery makes the condition of resource stocks threatened. This study aims to determine the parameter aspects of the population of several types of grouper fish in Labuan Bajo waters. The types of grouper studied included Plectropomus leopardus, P. maculatus, P. oligacanthus, and Variola albimarginata. Data collection was carried out by enumerators from April to August 2019 which included the daily data on the length and weight distribution of groupers. Length-frequency distribution data is analyzed by estimating fish population parameters using the Electronic Length Frequency Analysis (ELEFAN I) program which is packaged in the FAO-ICLARM Stock Assessment Tool II (FiSAT II) software. The results of the analysis showed the equation of growth parameters for Von Bartalanffy for P. leopardus is Lt = 89.06(1-e−0.24(t+0.52)); P. maculatus is Lt = 76(1-e−0.54(t+0.23)); P. oligacanthus is Lt = 72.32(1-e−0.66(t+0.19)); and V. albimarginata is Lt = 45(1-e−0.51(t+0.29)). The length at first birth of each species is Lt=0 P. leopardus = 10.45 cm, Lt=0 P. maculatus = 8.88 cm, Lt=0 P. oligacanthus = 8.52 cm, and Lt=0 V. albimarginata = 6.19 cm. Meanwhile, the exploitation rate (E) of P. leopardus, P. maculatus, P. oligacanthus, and V. albimarginata were 0.81; 0.53; 0.45; and 0.70.

Stock Assessment of Exploited Sardine Populations from Northeastern Bay of Bengal Water, Bangladesh Using the Length-Based Bayesian Biomass (LBB) Method

Stock assessment is necessary to understand the status of fishery stocks. However, for the data-poor fishery, it is very challenging to assess the stock status. The length-based Bayesian biomass (LBB) technique is one of the most powerful methods to assess the data-poor fisheries resources that need simple length frequency (LF) data. Addressing the present gap, this study aimed to assess the stock status of three sardines (Sardinella fimbriata, Dussumieria acuta, and D. elopsoides) in the Bay of Bengal (BoB), Bangladesh using the LBB method. The estimated relative biomass for S. fimbriata was B/B0 < BMSY/B0, indicating the overfished biomass, while the assessed B/B0 > BMSY/B0 for D. acuta and D. elopsoides indicates healthy biomass. Additionally, for S. fimbriata, the length at first landing was smaller than the optimum length at first landing (Lc < Lc_opt), indicating an overfishing status, but a safe fishing status was assessed for D. acuta and D. elopsoides (Lc > Lc_opt). Therefore, increasing the mesh size of fishing gears may help to ensure the long-term viability of sardine populations in the BoB, Bangladesh.

Abundance and Distribution, Growth Pattern, Sex Ratio and Gonadosomatic Index (GSI) of Liza falcipinnis (Valenciennes, 1836) from Ojo Axis of Badagry Creeks, Lagos, Nigeria

A study on seasonal abundance, morphometric and meristic data, growth pattern, condition factor, sex ratio and gonadosomatic index of Liza falcipinnis (Valenciennes, 1836) from the Ojo axis of Badagry creek, Nigeria was conducted from May 2019 to March 2020. A total of 1012 species were randomly selected, having 499 females and 513 males. The length frequency analysis and length-weight relationships (LWR) were determined. Sex ratio was determined by Chi-square analysis. The results showed that morphometric data are: 0.5 - 2.5 mm for ED, 2.1 - 12 mm for HL, 1.7 - 8.1 mm for HD, 2.5 - 11.7 for BD, 2.6 - 233.3 mm for TL and 9.23 - 1006 g for BW for the combined sexes. The slope (b) shows an allometric growth pattern. The intercept ‘a’ and slope ‘b’ of the LWR (LogW = a + bLogL) were Log W=15.39+ 0.34 LogL (r= 0.54) for combined sexes, Log W= 12.49+ 0.02 log L (r= 0.38) for males and Log W= 18.23+ 0.01 log L (r=0.16) for females.The length frequency distribution indicated that species were dominated by two year classes (Ages 1 and 2). Condition factors were generally low. The values ranged between 0.68 - 0.85 for combined sexes. The gonadosomatic index for female was highest in August, 2019 (17.77%) with Mean±SD of 2.88±0.75; which indicated the peak of spawning period in the study area.Sex ratio difference was significant (P<0.05). Sexual differences were significant; the females are phenotypically larger than the male.

Stock Assessment of 19 Perciformes in the Beibu Gulf, China, Using a Length-Based Bayesian Biomass Method

The Beibu Gulf in China is rich in fish resources. However, only a small number of commercially developed fish stocks have been specifically assessed owing to limited data and expertise. In this study, 19 perciform fish populations in the Beibu Gulf were assessed using a length-based Bayesian biomass (LBB) estimator method, which is a new approach to evaluate a fishery’s status using length frequency (LF) data. The results showed that only 21% of the evaluated stocks were healthy and 79% were overfished. In particular, 26 and 21% of the assessed species had collapsed and were grossly overfished, respectively. Only 11 and 21% of the assessed species were slightly overfished and overfished, respectively. The ratios between the mean and optimum length (Lmean/Lopt) and between the mean length at first capture and the mean length, which maximizes catch and biomass (Lc/Lc_opt), were below one in 14 out of the 19 stocks, suggesting a truncated length structure and fishing of undersized individuals. The ratio of the 95th percentile length to asymptotic length L95th/Linf was close to one (&gt;0.9) in 10 of 19 stocks, suggesting that at least some large fish were still present. Our research confirmed that the fishery resources in the Beibu Gulf were seriously overfished and provided evidence that LBB was an efficient method to evaluate the fishery resources. Fishery managers need to take specific measures to restore fishery resources.

Population characteristics and exploitation of yellowfin tuna (Thunnus albacares Bonnaterre, 1788) in the coastal waters of Kenya

Yellowfin tuna, Thunnus albacares (Bonnaterre, 1788) is a highly migratory and important commercial fishery species. Data on length-frequency, growth parameters and mortality rates of yellowfin tuna in the coastal waters of Kenya is limited. We assessed Catch Per Unit Effort (CPUE), size distribution, growth parameters and mortality rates based on length-frequency and catch data collected from August 2015 to December 2016 at five fish landing sites along the Kenyan coast. The sample comprised of 1281 individuals of yellowfin tuna weighing 12,671 kg. Highest CPUE was recorded in October 2015 (10.8 kg·Fisher-1Trip-1) and lowest CPUE, 2.6 kg·Fisher-1Trip-1 in December 2016. Yellowfin tuna was more abundant in the South-East Monsoon (SEM), from May to October, with an average CPUE of 7.3 kg Fisher-1Trip-1 compared to North East Monsoon (NEM), from November to April, with a CPUE of 7.0 kg Fisher-1Trip-1. Spatial variation of CPUE was evident. Old Town recorded the highest CPUE of 54.2 kgTrip-1, while Mnarani the lowest of 19.4 kgTrip-1. At least 91 % of the fish sampled were < 100 cm FL and hence not yet mature. The asymptotic Length (L∞) was found to be 195 cm FL, the Von Bertalanffy growth constant (K) 0.43 year-1, t0 - 0.82 and the Growth Performance Index (f) 4.21. The total mortality coefficient (Z) was 2.59 year-1 , Natural Mortality (M) 0.59 year-1, Fishing Mortality (F) 2.00 year-1 and Exploitation Rate (E) 0.77 year-1. Results show that mortality and exploitation rates were above the optimal, indicating high fishing pressure on coastal yellowfin tuna. The information generated by this study provides some further insights on the scientific knowledge of the coastal yellowfin tuna to inform policy for sustainable management and development of this fishery in Kenya and the entire South West Indian Ocean (SWIO) region.

Gillnet Selectivity on the Narrow-barred Spanish Mackerel (Scomberomorus commerson) Fishery in Pangandaran Waters

Analyzing the selectivity of gillnet fishing gear using two different mesh sizes, namely 3.5 and 4 inches. Gillnets of these mesh sizes are commonly used by fishermen in Fish Landing Base (PPI) Cikidang, Pangandaran Regency, West Jawa. A total of 8 fishing trips were conducted at the coastal waters around PPI Cikidang, Pangandaran Regency, West Java from August 2018 to January 2019 using gillnet fishing gear As for each trip, 2-3 times the operation of the tool is carried out. The operation of the fishing gear is carried out with the help of vessels measuring 2-3 Gross Tonnage (GT). The catch obtained was differentiated based on the main catch and bycatch and the amount is calculated for analysis of the proportion of the catch. Mackerel (Scomberomorus commerson) is caught as the main catch, the fork length was measured for analysis of the length frequency distribution and selectivity curves. The operation of gillnets with a mesh size of 3.5 inches obtained a higher proportion of bycatch compared to gillnets with a mesh size of 4 inches. In addition, the length distribution of mackerel caught by gillnets with a mesh size of 3,5 inches is smaller (27-49 cm FL) compared to a mesh size of 4 inches (40-55 cm FL). Based on the distribution of length distribution, gillnets with a mesh size of 3.5 inches are more dominant in catching mackerel in a smaller size class interval than gillnets with a mesh size of 4 inches. Meanwhile, based on the selectivity curve for the length of mackerel with a 50% chance of being caught, it shows that gillnets with a mesh size of 3.5 or 4 inches are selective in catching mackerel, this is because the chances of catching fish at more than L50 are high.