The response to capture and confinement stress of plasma cortisol, plasma sex steroids and vitellogenic oocytes in the marine teleost, red gurnard

Timing of Atlantic cod Gadus morhua seasonal migrations in relation to serum levels of gonadal and thyroidal hormones

“…Testosterone levels usually remained low in males as they departed the western Gulf in 1995and 1997). E 2 levels in females were also generally low at this time (Fig.…”

“…It appears that capture stress has a minimal effect on the circulating levels of both T 4 and T 3 (see Comeau et al 2000). Capture stress, however, is known to reduce the levels of gonadal hormones in various fishes (Pickering et al 1987, Pankhurst & Dedual 1994, Jardine et al 1996, Clearwater & Pankhurst 1997, Morehead 1998). Yet we note that testosterone levels in field-collected cod (this study) were generally higher than those reported for laboratory-held cod .…”

Seasonal changes in ovarian activity of New Zealand turbot(Colistium nudipinnis)and brill(C. guntheri)

“…Exceptions include studies on English sole (Parophrys vetulus) and (Xenentodon cancila) in which atresia of previtellogenic oocytes were common (Johnson et al 1991;Guraya 1993). Where excessive atresia Date has been identified in other species, it has resulted from stress (Clearwater & Pankhurst 1997;Pankhurst & Van Der Kraak 1997), pollutants (Das 1988;Sukumar & Karpagaganapathy 1992;Guraya 1993), and inadequate nutrition (Ma et al 1998). In the present study, fish were kept on ice for up to 4 days before ovarian samples were fixed for histology.…”

Dose-dependent effect of a single GnRHa injection on the spawning of meagre (Argyrosomus regius) broodstock reared in captivity

“…Stress is accepted as one of the principal factors that cause reproductive dysfunctions and that affect a GnRHa spawning protocol (Ibarra & Duncan, 2007;Mañanos et al, 2008;Mylonas et al, 2010). For example, the stress of capture has been shown to negatively affect reproductive endocrinology, decreasing estrodial and testosterone and oocyte development increasing oocyte atresia in red gurnard (Chelidonichthys kumu) (Clearwater & Pankhurst, 1997), female striped trumpeter (Latris lineate) (Morehead, 1998) and snapper (Pagrus auratus) (Cleary et al, 2000). In the present study, the stress from holding conditions and manipulations was the same for all fish in all treatment groups and the sham control (control 2.2) and the high spawning response indicates that the GnRHa protocols were successful in relation to these conditions and the stress that may have been caused by husbandry procedures and manipulation of the fish.…”