Interaction of the mormyrid fish Mormyrus kannume (Forsskål, 1775) reproduction and feeding intensity with the environment in a Nile Delta Canal,Egypt

Abstract

The effect of environmental factors on the fish biological parameters and their quantification was investigated in this study during the period from January 2005 to January 2006. Bahr Shebeen Canal is a Nile canal that represents a fishery resource in the Delta of Egypt, where Mormyrus kannume shows a scanty abundance. During the period from of June to September, there was a chance to examine such interaction. The obtained results revealed that the fish spawn over an extended period, from November till May, with two main peaks of spawning activity namely: November-December and February-April. Consequently, the gonadosomatic index (GSI) could not be correlated significantly with variation in either temperature or photoperiod. In those periods of spawning activity, the fish showed the lowest feeding intensity; i.e., low abundance. This was also quantified mathematically by significant correlations between the seasonal average (excluding winter) of stomachsomatic index (SSI) and either average daily temperature (T) and photoperiod (PP) for females and to a lower extent with males. These relationships were negatively correlated, and more significant among females than males, that was attributed to a higher activity of feeding among females. Also, the fish reproduction and feeding activities were correlated significantly with electrical conductivity and rainfall. This indicated that the fish are subject to the effect of associated environmental parameters interacting with their biology. The susceptibility of this fish species to change in those variables indicates its vulnerability to any adverse climatic change. The relationship between each of fecundity, egg diameter and gonadosomatic index and the female length or age were also examined and discussed, and the mathematical correlations were presented.

Sperm competition, sexual selection and the diverse reproductive biology of Osteoglossiformes

“…Speculatively, the energetics of electrogenesis and electroreception may require metabolic trade‐offs (Salazar et al ., 2013), and the ability to reproduce without producing sperm flagella may confer a metabolic fitness advantage (Montgomerie & Fitzpatrick, 2009). Evidence for low sperm competition in mormyrids is consistent with low GSI of about 0.5%, in M. kannume (Iles, 1960; Khallaf & Authman, 2012). Nonetheless, it is important to consider other life‐history traits, such as mating rate, that can conflate with GSI results (Parker & Pizzari, 2010).…”

“…Many osteoglossiform males demonstrate a low gonadosomatic index (GSI) (Adite et al ., 2006; Adjibade et al ., 2020; Hussain et al ., 2015; Khallaf & Authman, 2012; Opadokun & Ajani, 2015). Nonetheless, it is unclear how these values compare to other teleosts, because not all GSI reports consider cyclical fluctuations in gonad size.…”

A review of the reproductive biology of mormyroid fishes: An emerging model for biomedical research

“…As an individual progresses through the reproductive cycle, gonadal somatic index (GSI) fluctuates. GSI has been measured in several mormyroid species including Brienomyrus longianalis (Ikomi, 1996), Gymnarchus niloticus (Opadokun & Ajani, 2015), Hippopotamyrus ansorgii (Odedeyi & Odedire, 2017), Hyperopisus bebe occidentalis (Oniye & Onimisi, 2010), Marcusenius senegalensis (Adjibade et al, 2020), Mormyrus kannume (Khallaf & Authman, 2012), Mormyrus rume proboscirostris (Kirschbaum et al, 2008; Schugardt & Kirschbaum, 2004), and Pollimyrus isidori (Crawford et al, 1997). However, many authors do not report the phase of the reproductive cycle during which measurements were made and therefore comparison of these measurements is confounded.…”

“…As an individual progresses through the reproductive cycle, gonadal somatic index (GSI) fluctuates. GSI has been measured in several mormyroid species including Brienomyrus longianalis(Ikomi, 1996), Gymnarchus niloticus(Opadokun & Ajani, 2015), Hippopotamyrus ansorgii(Odedeyi & Odedire, 2017), Hyperopisus bebe occidentalis(Oniye & Onimisi, 2010), Marcusenius senegalensis(Adjibade et al, 2020), Mormyrus kannume(Khallaf & Authman, 2012), Mormyrus rume proboscirostris…”

Reproductive cycle of the broomtail wrasse, Cheilinus lunulatus inhabiting coral reef in Hurghada, Red Sea, Egypt.

“…The histological structure and seasonal variations of the teleostean gonads have attracted the attention of many investigations notably by Argyris (2005); Marcano et al (2007); Ramirez et al (2008); Mousa (2010); Khallaf et al (2012); Konan et al (2014) and Mohamed et al (2014).…”