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  Early stages of anchovy: abundance, variability and larval condition at the fixed coastal station EPEA between 2000-2017.

  Leonarduzzi, Ezequiel; Do Souto, Marina; Diaz, Marina V. (2021)

  MAFIS - Marine and Fishery Sciences

  Densities of eggs and larvae of Engraulis anchoita and the nutritional condition of larvae were analyzed in the fixed sampling station (EPEA) in the period 2000-2017. These variables were analyzed seasonally and trends over time were determined. Ichthyoplankton samples were collected by oblique trawls using Bongo nets with 300 μm of pore mesh and fixed with formaldehyde 5% in seawater. Six morphometric variables were measured to estimate the nutritional condition of larvae. The developmental stage of each specimen was also determined. The highest mean value of egg density was detected in the October-December period, with a secondary mode in August, followed by one in March. Larval density presented a mode in October. Autumn and spring were the most favorable seasons for larval condition while winter proved to be the least favorable one. An increase in food availability during autumn and spring due to primary and secondary production peaks could explain the high nutritional condition and growth values observed in these seasons at the EPEA. No changes in trends of variables over time were detected. The integrated study of density and nutritional condition of E. anchoita larvae allows the determination of favorable breeding periods for the species, while the continuation of the long term study will allow evaluating possible effects of climate change in the early life stages of this species.
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  Spatial and temporal distribution, size composition, and abundance of oval squid, Sepioteuthis lessoniana (Lesson 1830) in the coastal waters of Bolong, Zamboanga City, Philippines.

  Samson, Jesus Rolando (2019-07)

  The Palawan Scientist

  The study was conducted in the coastal waters of Bolong, Zamboanga City, Philippines purposely to determine the spatial distribution of Sepioteuthis lessoniana in relation to the depth of water and temporal distribution in relation to lunar phase using size composition and catch per unit effort (CPUE) data. Two sampling stations were established, namely, shallow-water station (Station 1) and deep-water station (Stations 2). Twenty units of squid traps were utilized in the study; ten of which were set in Station 1 and the other ten in Station 2. The traps were constructed using bamboo and green polyethylene netting. Instead of bait, coconut spikelet was placed inside the trap to lure squids. A motorized banca was used to set and haul the traps in the two sampling stations. Although hauling was done daily, sampling is scheduled only 12 times a month with three samplings per lunar phase. Catches were segregated according to sampling stations and lunar phases. Results of the study revealed that the squids caught in deeper waters were significantly larger than those caught in shallow waters, and that females dominated the shallow waters while males dominated the deeper waters. Furthermore, the catch during Full Moon was significantly higher than the catch of the other three lunar phases (p<0.05) with highest CPUE recorded in Station 2 during Full Moon (0.352 kg trap-1 day-1).
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  Backyard farming of tilapia using a biofloc-based culture system.

  Caipang, Christopher Marlowe; Avillanosa, Arlene (2019-07)

  The Palawan Scientist

  The pressures brought about by the increase in human population resulted in the rapid expansion of the food production industries including aquaculture to provide the nutritional requirements of the growing population. As aquaculture operations intensify, there is also an urgent need to preserve the environment; hence, all activities must be carried out in a sustainable way. The use of the biofloc technology (BFT) in aquaculture addresses these issues on restrictions on the usage of water and land as well as matters concerning sustainability of the production. BFT is a technique that maintains optimum water quality in the aquaculture system by manipulating the carbon and nitrogen ratios in the system. This optimum ratio favors the growth of heterotrophic bacteria that contribute in maintaining good water quality and at the same time provide sources of natural food for the cultured fish or crustaceans. In this review, the mechanisms of the biofloc technology particularly in the production of tilapia in freshwater systems are discussed. Moreover, some of the intrinsic advantages of this technology are highlighted in the context of developing and supporting backyard aquaculture of freshwater tilapias as a means of providing the food demands of the population in rural communities and as source of income for the marginalized small-scale fish farmers.
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  Water quality of Puerto Princesa Bay in relation to the presence of informal settlers in its coastal areas.

  Garcellano, Rhea; Japson, Loida; Wy, Siote (2022-06)

  The Palawan Scientist

  In this study, the water quality of four coastal areas in Puerto Princesa Bay, with and without informal settlers, were compared in terms of the phytoplankton composition and density, fecal coliform and physicochemical parameters during a 12-month sampling period. Microscopic examination and identification using phytoplankton monographs showed five harmful algal blooms (HABs) genera (Alexandrium, Dinophysis, Nitzschia, Pseudo-nitzschia, and Pyrodinium) with Dinophysis spp. as the most abundant in coastal areas with informal settlers and Pseudo-nitzschia spp. in areas without informal settlers. Eight phytoplankton genera (Coscinodiscus, Proboscia, Rhizosolenia, Skeletonema, Ceratium, Prorocentrum, Protoperidinium, and Oscillatoria) reported to have caused algal blooms were also observed with Coscinodiscus spp. as the most abundant in both groups of coastal areas. Multiple-tube fermentation technique showed fecal coliform count ranging from 4 to >1600 most probable number (MPN)/100 ml in the coastal areas with informal settlers and from <1.8 to 295 MPN/100 ml in areas without informal settlers. Multiprobe measurements showed that both groups of coastal areas have similar physicochemical characteristics with only the dissolved oxygen failing to meet the Philippine standards for class SB waters. There was a significant difference (P < 0.05) in water quality between the coastal areas with and without informal settlers in terms of fecal coliform and the density of four phytoplankton genera (Pseudo-nitzschia, Skeletonema, Alexandrium and Ceratium). However, there is no significant difference in terms of the physicochemical parameters. Regression analysis indicates that the presence of informal settlers could affect water quality in terms of fecal coliform and the five phytoplankton genera (Coscinodiscus, Pseudo-nitzschia, Skeletonema, Alexandrium and Ceratium).
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  Some biological aspects of bogue Boops boops (Linnaeus, 1758) from Saros Bay (Northern Aegean Sea, Turkey).

  Cengiz, Özgür (2022-06)

  The Palawan Scientist

  This study was conducted to determine the growth parameters, mortality and length at first maturity of bogue Boops boops (Linneaus, 1758) in Saros Bay (Northern Aegean Sea). A total of 363 specimens were obtained, monthly, from commercial fishermen between February 2016 and January 2017. The total length and weight of sampled fish ranged from 11.3 to 24.1 cm and from 16.61 to 165.32 g, with a mean of 16.9 cm and 60.40 g, respectively. The length-weight relationship was calculated as W = 0.0080TL3.13. The von Bertalanffy growth equations were computed to be 𝐿�∞ = 27.9 cm, k = 0.21 year-1, 𝑡�0 = -1.57 year. The growth performance index (𝛷�′) was found as 2.21. The length at first maturity was estimated as 16.6 cm. Total mortality rate (Z), natural mortality rate (M), fishing mortality rate (F) and exploitation rate (E) of the bouge were 0.44 year-1, 0.38 year-1, 0.06 year-1 and 0.13 year-1, respectively. The present study provides preliminary information on the growth parameters, mortality and length at first maturity of B. boops for the Saros Bay (Northern Aegean Sea, Turkey).

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