Evaluation of growth and production of the threatened giant river catfish, Sperata seenghala (Sykes) in polyculture with indigenous major carps

The giant river catfish locally named guizza, Sperata seenghala has significant cultural and economic importance but the fish is now considered as critically endangered due to environmental and manmade interventions in aquatic ecosystem. In order to conserve and rehabilitate this species, an experiment on polyculture of guizza with indigenous major carps was conducted in earthen ponds. Three treatments differing in species ratios and combinations of fish were employed with two replicates each. Treatment-1 (T1) was stocked with catla (Catla catla), rohu (Labeo rohita) and mrigal (Cirrhinus mrigala), treatment-2 (T2) with catla, rohu and guizza (S. seenghala), while treatment-3 (T3) with catla, rohu, mrigal and guizza. Guizza of T2 was introduced instead of mrigal in T1 and 50% of mrigal was replaced with guizza in T3. The stocking density of fish fingerlings in all the treatments was 7500 individual/ha. Fishes in the experimental ponds were fed with supplementary diet comprising of rice bran (50%), mustard oil cake (30%), fish meal (19%) and vitamin-mineral premix (1%). Physicochemical parameters and plankton populations were within the appropriate levels for aquaculture. Mean growth and survival of catla and rohu were significantly higher in T2 than in T3 and T1. Guizza in T2 showed higher performances than in T3, while those for mrigal were higher in T3 than T1 (p < 0.05). The total gross and net productions of fishes were higher in T3 than in T2 and T1 (p < 0.05). This trial is a successful attempt to culture the threatened guizza with major carps in earthen ponds, the findings of which would immensely be helpful towards the development of aquaculture and conservation of this important fish in captive condition.Key words: Riverine catfish, Sperata seenghala, polyculture, earthen 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

Integrated Ecosystem Assessment: Lake Ontario Water Management

BACKGROUND: Ecosystem management requires organizing, synthesizing, and projecting information at a large scale while simultaneously addressing public interests, dynamic ecological properties, and a continuum of physicochemical conditions. We compared the impacts of seven water level management plans for Lake Ontario on a set of environmental attributes of public relevance. METHODOLOGY AND FINDINGS: Our assessment method was developed with a set of established impact assessment tools (checklists, classifications, matrices, simulations, representative taxa, and performance relations) and the concept of archetypal geomorphic shoreline classes. We considered each environmental attribute and shoreline class in its typical and essential form and predicted how water level change would interact with defining properties. The analysis indicated that about half the shoreline of Lake Ontario is potentially sensitive to water level change with a small portion being highly sensitive. The current water management plan may be best for maintaining the environmental resources. In contrast, a natural water regime plan designed for greatest environmental benefits most often had adverse impacts, impacted most shoreline classes, and the largest portion of the lake coast. Plans that balanced multiple objectives and avoided hydrologic extremes were found to be similar relative to the environment, low on adverse impacts, and had many minor impacts across many shoreline classes. SIGNIFICANCE: The Lake Ontario ecosystem assessment provided information that can inform decisions about water management and the environment. No approach and set of methods will perfectly and unarguably accomplish integrated ecosystem assessment. For managing water levels in Lake Ontario, we found that there are no uniformly good and bad options for environmental conservation. The scientific challenge was selecting a set of tools and practices to present broad, relevant, unbiased, and accessible information to guide decision-making on a set of management options

Neural processing of natural sounds

Natural sounds include animal vocalizations, environmental sounds such as wind, water and fire noises and non-vocal sounds made by animals and humans for communication. These natural sounds have characteristic statistical properties that make them perceptually salient and that drive auditory neurons in optimal regimes for information transmission.Recent advances in statistics and computer sciences have allowed neuro-physiologists to extract the stimulus-response function of complex auditory neurons from responses to natural sounds. These studies have shown a hierarchical processing that leads to the neural detection of progressively more complex natural sound features and have demonstrated the importance of the acoustical and behavioral contexts for the neural responses.High-level auditory neurons have shown to be exquisitely selective for conspecific calls. This fine selectivity could play an important role for species recognition, for vocal learning in songbirds and, in the case of the bats, for the processing of the sounds used in echolocation. Research that investigates how communication sounds are categorized into behaviorally meaningful groups (e.g. call types in animals, words in human speech) remains in its infancy.Animals and humans also excel at separating communication sounds from each other and from background noise. Neurons that detect communication calls in noise have been found but the neural computations involved in sound source separation and natural auditory scene analysis remain overall poorly understood. Thus, future auditory research will have to focus not only on how natural sounds are processed by the auditory system but also on the computations that allow for this processing to occur in natural listening situations.The complexity of the computations needed in the natural hearing task might require a high-dimensional representation provided by ensemble of neurons and the use of natural sounds might be the best solution for understanding the ensemble neural code

Neurophysiological response selectivity for conspecific songs over synthetic sounds in the auditory forebrain of non-singing female songbirds

Female choice plays a critical role in the evolution of male acoustic displays. Yet there is limited information on the neurophysiological basis of female songbirds’ auditory recognition systems. To understand the neural mechanisms of how non-singing female songbirds perceive behaviorally relevant vocalizations, we recorded responses of single neurons to acoustic stimuli in two auditory forebrain regions, the caudal lateral mesopallium (CLM) and Field L, in anesthetized adult female zebra finches (Taeniopygia guttata). Using various metrics of response selectivity, we found consistently higher response strengths for unfamiliar conspecific songs compared to tone pips and white noise in Field L but not in CLM. We also found that neurons in the left auditory forebrain had lower response strengths to synthetics sounds, leading to overall higher neural selectivity for song in neurons of the left hemisphere. This laterality effect is consistent with previously published behavioral data in zebra finches. Overall, our results from Field L are in parallel and from CLM are in contrast with the patterns of response selectivity reported for conspecific songs over synthetic sounds in male zebra finches, suggesting some degree of sexual dimorphism of auditory perception mechanisms in songbirds.Mark E. Hauber, Phillip Cassey, Sarah M. N. Woolley and Frederic E. Theunisse