Larval Fish Composition, Distribution and Diets in the Seagrass-Mangrove Ecosystem of Gelang Patah, Johor, Malaysia

Fish larval composition, spatio-temporal distribution, density, family richness, Shannon-Wiener index and feeding habits were determined by analyzing samples collected from the seagrass-mangrove ecosystem of Gelang Patah, Johor Strait, Peninsular Malaysia between October 2007 and September 2008. Five stations were selected namely Upper estuary (S1), middle estuary (S2) and lower estuary (S3) of Pendas River; seagrass beds (S4) and open seas (S5). Each sampling station was approximately 1 km apart from each other. Fish larvae were collected by subsurface towing of bongo net equipped with a flow meter. In total, 24 families of fish larvae belong to six orders were identified from seagrass-mangrove ecosystem of Gelang Patah, Johor Strait. Similarity matrix and cluster analysis revealed that there are six different families under the order Perciformes. In total, 24 families were identified from the coastal waters of Gelang Patah, Johor, Peninsular Malaysia. Among them, 14 occurred in upper estuary, 17 in middle estuary, 16 in lower estuary, 20 in seagrass beds and 16 in open sea. Overall five (Clupeidae, Blenniidae, Terapontidae, Gobiidae and Sillaginidae) were the most dominant in study areas. Shannon-Wiener index varied significantly within monsoon and intermonsoon seasons peaking in the months October-January and May-August. The highest density of larval fishes was recorded at seagrass station (S4) and the spatial variations in larval density were significant (p < 0.05) between seagrass and other four sampling sides. None of the diversity indices showed significant among-stations except only family richness was significantly (p < 0.05) higher in seagrass beds than upper estuary. Among 24 families, 18 families were found to have correlation either positively or negatively with the water parameters. The highest and significant regression coefficient was observed in Sillaginidae which indicated 72% abundance of Sillaginidae was influenced by the major water parameters and remaining 28% by other factors. In total, 267 Blenniidae, 401 Clupeidae, 126 Gobiidae and 117 Terapontidae stomachs were examined during the study period. Analyses of prey in the stomachs identified 24 important items (%Rs > 0.05) belonging to six major groups: phytoplankton, zooplankton, algae, plant like matter, debris and unidentified materials. According to the Simple Resultant Index (%Rs), the predominant food item in the stomach of all four families (Blenniidae, Clupeidae, Gobiidae and Terapontidae) was phytoplankton (> 60%). This was followed by zooplankton in Blenniidae (18.24%) and Clupeidae (8.60%). On the other hand, the second diet composition was plant like matter in Gobiidae (14.73%) and Terapontidae (8.02%). Among phytoplankton, Dacytyloccopsis fasicularis (26.31%) was large quantity in the stomachs of Bleniidae and this was followed by Nitzschia baccata (23.38%). Conversely, Nitzschia sp. was the highest quantity (26.33%) in the stomachs of Clupeidae larvae and subsequently Dacytyloccopsis fasicularis (13.56%), Biddulphia sinensis (10.51%), Rhizosolenia araturensis (8.63%), Lauderia borealis (8.06%) and Fragilaria intermedia (3.47%). In Gobiidae larvae, Chromophyta (28.30%) was observed as the highest quantity and second highest component was Nitzschia sp. (15.97%) and then Dacytyloccopsis fasicularis (8.27%). Similarly, Chromophyta (29.12%) was the highest quantity in the stomachs of Terapontidae (Table 6.17). Second and third component was Nitzschia sp. (15.95%) and Dacytyloccopsis fasicularis (13.80%). Overall, two most dominant phytoplankton (Dacytyloccopsis fasicularis and Nitzschia sp.) was observed among the four larval families. It is revealed that various food items were found in the stomachs of Bleniidae, Clupeidae, Gobiidae and Terapontidae larvae and remarkable that phytoplankton were more than 60% in the diet composition. Therefore, all studied fish larval families in the study areas are exclusively herbivore

Composition and diversity of larval fish in the mangrove estuarine area of Marudu Bay, Sabah, Malaysia

The composition of fish larvae and their diversity in different habitats are very important for fisheries management. Larval fishes were investigated in a mangrove estuary of Marudu Bay, Sabah, Malaysia from October 2012 to September 2013 at five different sites. Monthly samples of fish larvae were collected at five sampling sites by a plankton net with a mouth opening of 40.5 cm in diameter. In total, 3879 larval fish were caught in the investigated area. The mean density of ichthyoplankton at this area was 118 larvae/100 m(3). The fish larval assemblage comprised of 20 families whereas 13 families occurred at St1, 16 at St2, 16 at St3, 12 at St4 and 16 at St5. The top major families were Sillaginidae, Engraulidae, Mugilidae and Sparidae with Sillaginidae consisted 44% of total larval composition. St3 with 143 larvae/100 m(3) had the highest density amongst the stations which was due to higher abundance of Sillaginidae. Shannon-Wiener diversity index represented significant variation during monsoon and inter-monsoon seasons, peaking in the months December-January and May-June. However, Shannon-Wiener index, evenness and family richness showed significant differences among stations and months (p < 0.05)

Development of breeding and fingerling production techniques for endangered long-whiskered catfish Sperata aor in captivity

An experiment was undertaken to develop a suitable seed production technique for Sperata aor in captivity. Naturally produced fry of aor was reared at different densities in nine nursery ponds 0.012 ha in size with an average depth of 0.8 m each. Three stocking densities tested, each of which was triplicated. Fry of aor stocked at 100,000/ha was designated as treatment-1 (T1), 150,000/ha as treatment-2 (T2) and 200,000/ha as treatment-3 (T3). All stocked fry were from the same age group with mean length and weight of 1.78 ± 0.28 cm and 0.24 ± 0.05 g, respectively. Fry in all the treatments were fed with SABINCO nursery feed (32.06% crude protein) for the first 14 days and starter-I (31.53% crude protein) for days 15 to 56. Physico-chemical parameters and plankton population of pond water were within the optimal level being better in T1 than those in T2 and T3. Growth in terms of final weight and length, weight and length gain, specific growth rate, daily growth rate, and survival of fingerlings were significantly higher in T1 followed by T2 and T3. Food conversion rate was significantly lower in T1 than in T2 and T3. Significantly higher number of fingerlings was produced in T3 than those in T2 and T1. Despite this, consistently higher net benefits were achieved from T1 than from T2 and T3. This is the first time report that stocking of 100,000 fry/ha appears to be the most suitable density for rearing of aor fingerlings in nursery ponds

A snapshot study on larval fish diversity in selected mangrove areas of Peninsular Malaysia, Malaysia / Izzati Adilah Azmir... [et al.]

The study on composition, abundance and diversity of larval fish was conducted with the aim to attain information on larval fish breeding ground and made easy for fishery management. Larval fish were collected during September 2015 from mangrove areas of Pekan Pahang, Pendas Johor, Matang Perak and Setiu Terengganu using a bongo net, towed at a depth of about 0.5 m from the surface for 5 min against the tidal flow. A total of 354 larval fish were collected, representing 21 families and 51 species. The top 3 families were Gobiidae (39.26%), Engraulidae (14.97%) and Clupeidae (14.40%), occurred in all sampling areas except in Setiu. The most abundant 11 species formed about 50% of all collected larval fish. Gobiidae spp. were the most abundant, making up 17.8% of the total catch, followed by Clupeidae spp. (12.7%), Engraulidae spp. (8.2%), Ambassis dusumieri (6.5%), Thryssa kammalensis (4.8%), Pseudogobius masago (both 4.8%), Sillaginidae spp. (4.2%), Ambassidae spp. (3.4%), Pseudogobius sp. (3.4%), Blenniidae spp. (2.8%), and Hemigobius hoevenii (2.5%). The highest diversity of larval fish was recorded for Pendas, Johor with Shannon Wiener index Hs = 2.699, and the lowest was Setiu, Terengganu (Hs = 0.832). The highest evenness index of larval fish species was recorded for Pekan, Pahang with Es = 0.815 and the lowest for Setiu Terengganu with Es = 0.465, indicating high single-species dominance. Species overlapping was the highest between Pendas and Setiu at 14.3%, and zero similarity of fish composition was recorded between Matang and Setiu according to Jaccard coefficient. Findings from surveillance of larval fish species provide valuable information for future biodiversity studies and allow better management of biodiversity resources in the mangrove ecosystem of Malaysia

Food and feeding habits of Omobranchus sp. (Blenniidae: Omobranchini) larvae in the seagrass-mangrove ecosystem of Johor Strait, Malaysia

The stomach contents of Omobranchus sp. (family Blenniidae) larvae were investigated in a seagrass-mangrove based ecosystem in Johor Strait, Malaysia from October 2007 to September 2008. Specimens of larval fish were collected through subsurface towing of a Bongo net from five different stations. The stomach sacs of 267 Omobranchus sp. larvae were separated and observed, which comprised of 24 significant food stuffs belonging to 6 main groups viz. phytoplankton (62.45%), zooplankton (18.24%), algae (5.56%), plant-like particles (5.75%), debris (4.22%) and unidentified particles (2.03%). In situ water parameters were also measured throughout the sampling cruises. There was a strong and significant positive correlation between stomach phytoplankton and salinity (r = 0.658, p < 0.05).? Canonical correlation analysis indicated a weak relationship (29.8%) between stomach contents and physico-chemical parameters. Only salinity appeared to be the controlling factor for the stomach contents of Omobranchus sp. larvae in the investigated area. Based on the stomach content analysis, it could be concluded that Omobranchus sp. were mainly herbivorous during the larval stages

Development of digestive tract of hilsa shad, Tenualosa ilisha (Hamilton 1822) fry in the lower Meghna estuary, Bangladesh

This study was designed to describe the morphological development of the gut of Hilsa, Tenualosa ilisha from yolk sac to early juvenile stage. Samples were collected from the lower Meghna River, Bangladesh and laboratory analysis was conducted at Universiti Putra Malaysia, Malaysia. Digestive tract was transparent and straight tube in structure at yolk sac stage. After yolk sac absorption, the digestive tract was differentiated into mouth opening, buccopharyngeal cavity, esophagus, stomach, intestines and rectum. Development of digestive tract was almost completed during pre-flexion stage. Gut loop was clearly observed at post flexion stage. Digestive tract was equal to more than three-quarter of standard length during larval development. The percentage of gut length compared with the standard length were 84.87 ± 4.87 %, 85.64 ± 4.47 %, 82.29 ± 6.18 %, 77.99 ± 4.98 %, 74.02 ± 3.27 % at yolk sac, preflexion, flexion, post- flexion and juvenile stages, respectively. There was a strong linear relationship between the gut length and standard length (R2 = 0.97). This is the first report on morphological changes of gut and its development of T. ilisha larvae, which might be very useful information for aquaculture development of T. ilisha

Environment and diversity of ichthyoplankton in the seagrass beds of Sungai Pulai Estuary, Johor, Peninsular Malaysia.

Larval fish composition, seasonal diversity and their abundance influenced by environmental parameters were investigated between October 2007 and September 2008 in the Sungai Pulai seagrass beds of Johor, Malaysia. Fish larvae were collected monthly by a bongo net through 30 min surface tows in the seagrass beds. In situ environmental variables were recorded during the sampling cruises. Habitat temperatures of fish larvae ranged from 26.92-30.83°C (Mean ± SE, 29.11 ± 0.34°C); dissolved oxygen ranged from 4.73 to 7.19 mgL-1 (5.96 ± 0.19 mgL-1) and the salinity fluctuation was between 27.38 and 33.67 ppt (30.64 ± 0.50 ppt). In total 2,801 larvae, belonging to 20 families were recorded, with a mean abundance of 79 individuals/100 m3. Top six families (Clupeidae, Terapontidae, Nemipteridae, Sillaginidae, Blenniidae and Gobiidae) occurred consistently around the year. Larvae belonging to family Clupeidae (47.94%) and Terapontidae (17.35%) were most abundant in the study area. The density of total larval fishes varied significantly (P<0.05) among the different months. The highest diversity index (1.99) was observed in July while the lowest (1.20) was observed in September. Mean body length of larval fishes was 3.34 ± 0.51 mm (Mean ± SE) and ranged from 1.20 to 15.52 mm. It is revealed that 45% of the individuals were less than 4 mm and 99% were less than 6 mm (TL). The abundance of dominant families was found to have correlation (positive or negative) with the water parameters. Regular occurrence of larvae of different size range confirms the continuous spawning activity in this seagrass area

Food habits of snakehead, Channa striatus (Bloch), in the lotic streams of Universiti Putra Malaysia, Malaysia

Stomach contents were used to investigate the food and feeding habits of Channa striatus, collected from the lotic streams in Ladang 10, Universiti Putra Malaysia, Malaysia. Samples were collected twice a month between September and November 2012. In total, 120 stomachs of C. striatus both adults and fry were examined. Analysis of preys in stomach showed 7 major food items for both adults and fry of C. striatus. The most important diet of fry according to the simple resultant index (%Rs) was copepods (23.37%). This was followed by cladocerans (20.52%), insects (20.07%), molluscs (13.70%), worms (9.58%), shrimps (9.12%) and others (3.65%). Predominant diet found in the stomach of adult was aquatic insects (27.46%). This was followed by shrimps (22.51%), small fish (17.48%), others (15.55%), semi digested materials (11.25%), worms (3.31%) and part of fish (2.43%). The feeding intensity was very poor in adult fishes during the experimental period. The fry fed actively throughout the study period where most of them were found to be full stomach. It could be concluded that both fry and adult C. striatus are carnivorous

Development of captive breeding and seed production techniques for Giant River Catfish Sperata seenghala

The Giant River Catfish Sperata seenghala, locally known as “Guizza Air” (and hereafter referred to as just Guizza), has significant aquacultural and conservational values, but closer monitoring of the fish is now badly needed. To protect the species from extinction, an experiment was undertaken to breed and produce seed of Guizza in a captive-rearing system. In our study, Guizza were successfully bred and the naturally produced fry were reared at different stocking densities in nine earthen nursery ponds having an area of 0.012 ha each with an average depth of 0.8 m. Three stocking densities were evaluated in three replicates each. Fry produced from natural propagation that were stocked at 100,000/ha were defined as treatment 1 (T1), those stocked at 150,000/ha as treatment 2 (T2), and those stocked at 200,000/ha as treatment 3 (T3). At stocking, all reared fry were of the same age-group with a mean±SD length and weight of 1.74±0.27 cm and 0.20±0.03 g, respectively. Fry in all the experimental ponds were reared with commercial Saudi Bangla (SABINCO) nursery feed (32.06% crude protein) for the first 14 d and starter-I (31.53% crude protein) for days 15–56. Growth (final weight, final length, weight gain, length gain, and specific growth rate) and survival of the fingerlings were significantly higher in T1 than in T2 and T3. Feed conversion rate was significantly lower in T1 than in T2 and T3. Moreover, the physicochemical measurements and plankton population of the pond water were within the optimal level for fish culture, with plankton abundance being higher in T1 than in T2 and T3. Consistently higher net benefits were obtained from T1 than from T2 and T3. Hence, of the three stocking densities, 100,000 fry/ha was the most suitable density for rearing Guizza fingerlings in nursery ponds

Influence of environmental parameters on shrimp post-larvae in the Sungai Pulai seagrass beds of Johor Strait, Peninsular Malaysia

Monthly sampling for shrimp post-larvae was conducted between April 2007 and March 2008 from the seagrass beds of Sungai Pulai Estuary, Johor, Peninsular Malaysia. Samples were collected from sub-surface using a bongo net equipped with a flow meter. In situ environmental parameters such as water temperature, dissolved oxygen, pH, salinity, total dissolved solid and conductivity were recorded during each sampling time. Total catch was comprised of four major taxa namely:Lucifer (94.9%), Acetes (1.52%), Penaeus (0.13%) and Mysis (0.06%). Mean density of shrimp post larvae (PL) was calculated as 22,614.74 individuals/100 m3. Peak abundance of Penaeus was found in June to July, while Acetes was found throughout the year with peak abundance in September. Higher abundance ofLucifer compared to the other genus was observed throughout the year with peaks in the monsoon months (May to July and October to December). The occurrence and abundance of Mysis was also restricted only in the monsoon months (November to January and May to July). There were significant correlation between the abundance of shrimp PL and in situ environmental parameters in the study area