Some aspects of the reproductive biology of &lt;i&gt;Tilapia zilli&lt;/i&gt; from a Small Lake in Imo State, Nigeria

Anene, Afamdi; Keke, RI

doi:10.4314/apra.v1i2.36295

Cited by 7 publications

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“…This is in agreement with Nikolsky [30] who reported that the sex ratio may vary from year to year in the same population, but in most fish species it is close to one, for example in the rainbow selebensis, T. celebensis [12], Protopterus annectens [31] and Oreochromis niloticus [32]. However, the sex ratio of R. tawarensis showed a predominance of female, a similar trend to that reported for Tilapia mariae [33], A. fasciatus [28] and Pellonula leonensis [34]. In contrast, in Abudefduf saxatilis [35] and T. putitora [22], the number of male was higher than female.…”

Section: Discussionsupporting

confidence: 89%

Spawning seasons of Rasbora tawarensis (Pisces: Cyprinidae) in Lake Laut Tawar, Aceh Province, Indonesia

Muchlisin

Musman

Azizah

2010

Reprod Biol Endocrinol

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BackgroundRasbora tawarensis is an endemic freshwater fish in Lake Laut Tawar, Aceh Province, Indonesia. Unfortunately, its status is regarded as critical endangered with populations decreasing in recent years. To date no information on the spawning activities of the fish are available. Therefore, this study provides a contribution to the knowledge on reproductive biology of R. tawarensis especially on spawning seasons as well as basic information for conservation of the species.MethodsMonthly sampling was conducted from April 2008 to March 2009 by using selective gillnets. The gonadosomatic index, size composition and sex ratio were assessed. The gonadal development was evaluated based on macroscopic and microscopic examinations of the gonads.ResultsThe gonadosomatic index (GSI) varied between 6.65 to 18.16 in female and 4.94 to 8.56 for male. GSI of the female R. tawarensis was higher in March, September and December indicating the onset of reproductive seasons, the GSI and oocyte size being directly correlated with gonadal development stages. Although, a greater proportion of mature male than female was detected during the study, the sex ratio showed that the overall number of female was higher than male. The ovaries had multiple oocyte size classes at every stage of gonadal development, thus R. tawarensis can be classified as a group synchronous spawner or a fractional multiple spawner.ConclusionThe spawning seasons of R. tawarensis were three times a year and September being the peak of the reproductive season and the female was the predominant sex. This species is classified as a group synchronous spawner.

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Section: Discussionsupporting

confidence: 89%

Spawning seasons of Rasbora tawarensis (Pisces: Cyprinidae) in Lake Laut Tawar, Aceh Province, Indonesia

Muchlisin

Musman

Azizah

2010

Reprod Biol Endocrinol

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“…A similar trend has been documented in some reproductive studies of T. mariae in its native range (Ikomi & Jessa, 2003; King & Etim, 2004). This bias in sex ratios may be due to a range of factors including differences in natural mortality or longevity between the sexes (King & Etim, 2004; Anene & Okorie, 2008) or, as previously discussed for O. mossambicus , could be related to environmental stresses. It has also been suggested that fishing activity has been responsible for selectively removing males, which dominate the larger size classes thereby biasing sex ratios (Anene & Okorie, 2008).…”

Section: Discussionmentioning

confidence: 89%

“…This bias in sex ratios may be due to a range of factors including differences in natural mortality or longevity between the sexes (King & Etim, 2004; Anene & Okorie, 2008) or, as previously discussed for O. mossambicus , could be related to environmental stresses. It has also been suggested that fishing activity has been responsible for selectively removing males, which dominate the larger size classes thereby biasing sex ratios (Anene & Okorie, 2008). This is unlikely to be a major contributing factor in Queensland where it is illegal to possess T. mariae .…”

Section: Discussionmentioning

confidence: 89%

“…The current study documented an extended spawning season for T. mariae in both Lake Tinaroo and particularly in the Mulgrave River where there is reproductive activity over most of the year. In African rivers and streams, spawning appears to peak during the wet season (Turner & Robinson, 2000; Ikomi & Jessa, 2003; King & Etim, 2004; Anene & Okorie, 2008). Anene & Okorie (2008) reported that in a small man‐made lake in Nigeria, T. mariae spawned year‐round with a series of slightly lower I G values during the dry season.…”

Section: Discussionmentioning

confidence: 99%

“…In African rivers and streams, spawning appears to peak during the wet season (Turner & Robinson, 2000; Ikomi & Jessa, 2003; King & Etim, 2004; Anene & Okorie, 2008). Anene & Okorie (2008) reported that in a small man‐made lake in Nigeria, T. mariae spawned year‐round with a series of slightly lower I G values during the dry season. In Lake Tinaroo, the I G values both peaked during the wet season (February) before dropping considerably in March but the gonad staging suggests some spawning over much of the year.…”

Section: Discussionmentioning

confidence: 99%

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Reproductive strategies of two invasive tilapia species Oreochromis mossambicus and Tilapia mariae in northern Australia

Russell

Thuesen

Thomson

2012

Journal of Fish Biology

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The reproductive biology of two invasive tilapia species, Oreochromis mossambicus and Tilapia mariae, resident in freshwater habitats in north-eastern Australia was investigated. Oreochromis mossambicus exhibited plasticity in some of its life-history characteristics that enhanced its ability to occupy a range of habitats. These included a shallow, weed-choked, freshwater coastal drain that was subject to temperature and dissolved oxygen extremes and water-level fluctuations to cooler, relatively high-altitude impoundments. Adaptations to harsher conditions included a decreased total length (L(T) ) and age (A) at 50% maturity (m50), short somatic growth intervals, early maturation and higher relative fecundities. Potential fecundity in both species was relatively low, but parental care ensured high survival rates of both eggs and larvae. No significant difference in the relative fecundity of T. mariae populations in a large impoundment and a coastal river was found, but there were significant differences in relative fecundities between several of the O. mossambicus populations sampled. Total length (L(T) ) and age at 50% maturity of O. mossambicus populations varied considerably depending on habitat. The L(Tm50) and A(m50) values for male and female O. mossambicus in a large impoundment were considerably greater than for those resident in a small coastal drain. Monthly gonad developmental stages and gonado-somatic indices suggested that in coastal areas, spawning of O. mossambicus and T. mariae occurred throughout most of the year while in cooler, high-altitude impoundments, spawning peaked in the warmer, summer months. The contribution these reproductive characteristics make to the success of both species as colonizers is discussed in the context of future control and management options for tilapia incursions in Australia.

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Age and growth of two newly established invasive populations of Tilapiamariae in northern Australia

Russell

Thomson

Thuesen

2013

Journal of Fish Biology

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Sagittal otoliths were used to age the samples of Tilapia mariae collected from a coastal river and an impoundment. Validation of sagittae checks was achieved using both quantitative marginal increment analysis and by tetracycline marking of the otoliths of fish kept in tanks and in a farm dam. The annulus pattern on the otoliths was generally clear and their formation appeared to be temperature related and largely completed in the Austral spring around September and October. Male T. mariae grow faster and larger than females and the maximum ages of fish from the coastal river and impoundment was 9+ and 4+ years, respectively. Past fish surveys and the absence of older age classes in the impoundment population would suggest that this population was only very recently established.

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Some aspects of the reproductive biology of <i>Tilapia zilli</i> from a Small Lake in Imo State, Nigeria

Cited by 7 publications

References 0 publications

Spawning seasons of Rasbora tawarensis (Pisces: Cyprinidae) in Lake Laut Tawar, Aceh Province, Indonesia

Spawning seasons of Rasbora tawarensis (Pisces: Cyprinidae) in Lake Laut Tawar, Aceh Province, Indonesia

Reproductive strategies of two invasive tilapia species Oreochromis mossambicus and Tilapia mariae in northern Australia

Age and growth of two newly established invasive populations of Tilapiamariae in northern Australia

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