Regional differences in the reproductive parameters of the sparsely-spotted stingaree, Urolophus paucimaculatus, from south-eastern Australia

Differences in the reproductive biology of both the Australian weasel shark Hemigaleus australiensis and the Australian sharpnose shark Rhizoprionodon taylori were apparent between individuals from the southern-most extent of their range in eastern Australia (Moreton Bay) and those from northern Australia. For H. australiensis from Moreton Bay the total length (L ) at which 50% of individuals were mature (L ) was 759 mm for females and 756 mm for males, values that were respectively 17-26% larger than reported for the species in northern Australia. The relatively low percentage (63%) of pregnant mature females and presence of small, similar-sized, embryos in utero in both May and November suggested a semi-synchronous, annual reproductive cycle in Moreton Bay, whereas a synchronous, biannual reproductive cycle occurred in northern Australia. It is likely that H. australiensis has a resting phase between gestation cycles at the southern-most extent of its range. For R. taylori from Moreton Bay the L s were 588 and 579 mm for females and males, respectively, values 2-3% larger than for individuals from the mid-Queensland coast and 31-35% larger than for individuals from northern Australia. The length at which 50% of the females were maternal (611 mm L ) in Moreton Bay was greater than the L , indicating that not all sharks mate immediately after maturing. Rhizoprionodon taylori in the south had an annual reproductive cycle incorporating a 7-8 month embryonic diapause, with pups probably born in February. A mean fecundity of 7·5 was almost double that reported from northern Australia. Regional variations in the reproductive characteristics of H. australiensis and R. taylori may influence their resilience to fishing and other anthropogenic pressures. The substantial differences reported here highlight the importance of region-specific life-history parameters to successful management and conservation.

Section: At I T U D I Na L Va R I At I O N I N R E P Ro D U C T I O Nmentioning

confidence: 69%

“…(b)]. Elasmobranchs have been reported to abort some or all of their pups when under capture stress (Conrath & Musick, ; Trinnie et al ., ); however, as both the current and previous studies used similar sampling techniques, it is unlikely that the observed differences in fecundity could be attributed to a different amount of capture stress.…”

Section: Discussionmentioning

confidence: 99%

Living on the edge: latitudinal variations in the reproductive biology of two coastal species of sharks

Taylor

Harry

Bennett

2016

“…Litter size declined from two to six embryos for early‐term pregnancies, one to four for mid‐term to one to two for late‐term (White et al , ). Trinnie et al (), however, report that observations from south‐east Australian urolophids show similar litter sizes during early and late‐term and as such, the higher reported litter sizes in that region are considered accurate by those authors.…”

Section: Discussionmentioning

confidence: 96%

“…Larger maximum litter sizes have been reported for several species off south‐east Australia, including six to seven for T. imitata (Trinnie et al , ) and 11–13 for U . gigas (Trinnie et al , ). For U .…”

Section: Discussionmentioning

confidence: 99%

Reproductive parameters of rhinobatid and urolophid batoids taken as by‐catch in the Queensland (Australia) east coast otter‐trawl fishery

Kyne

Courtney

Jacobsen

et al. 2016

Reproductive variables are provided for batoids regularly taken as by-catch in the east coast otter-trawl fishery on the inner-mid continental shelf off the south-east and central coasts of Queensland, Australia. Total length at maturity (LT50 and 95% c.i.) for the eastern shovelnose ray Aptychotrema rostrata was 639·5 mm (617·6-663·4 mm) for females and 597·3 mm (551·4-648·6 mm) for males. Litter size (n = 9) ranged from nine to 20 (mean ± s.e. = 15·1 ± 1·2). This species exhibited a positive litter size-maternal size relationship. Disc width at maturity (WD50 and 95% c.i.) for the common stingaree Trygonoptera testacea was 162·7 mm (155·8-168·5 mm) for females and 145·9 mm (140·2-150·2 mm) for males. Gravid T. testacea (n = 6) each carried a single egg in the one functional (left) uterus. Disc width at maturity (WD50 and 95% c.i.) for the Kapala stingaree Urolophus kapalensis was 153·7 mm (145·1-160·4 mm) for females and 155·2 mm (149·1-159·1 mm) for males. Gravid U. kapalensis (n = 16) each carried a single egg or embryo in the one functional (left) uterus. A single female yellowback stingaree Urolophus sufflavus carried an embryo in each uterus. A global review of the litter sizes of shovelnose rays (Rhinobatidae) and stingarees (Urolophidae) is provided.

“…Other factors should be considered, such as differences in habitat preference between sexes in adulthood, as well as differential mortality between sexes due to fishing practices and stocks living under different environmental conditions. Differences in population parameters have been found for other elasmobranchs (Lombardi‐Carlson et al ., ; Carlson et al ., ; Frisk & Miller, ; Licandeo & Cerna, ; McPhie & Campana, ; Trinnie et al ., , ). It is possible that there are different stocks of U. microphthalmum throughout the area of distribution, so there is a need for population and genetic studies.…”

Section: Discussionmentioning

confidence: 99%

Reproductive biology of Urotrygon microphthalmum (Batoidea: Urotrygonidae) from north‐eastern Brazil, tropical west Atlantic Ocean

Santander‐Neto

Araújo

Lessa

2016

The reproductive biology of Urotrygon microphthalmum was studied based on specimens caught as by-catch in shrimp (Litopenaeus schmitti, Xiphopenaeus kroyeri, Farfantepenaeus subtilis and Farfantepenaeus brasiliensis) fishing operations between March 2010 and March 2012 on the coast of Pernambuco, Brazil. Females reached a larger total length (LT ) and total body mass (MT ) (298 mm and 148 g) than males (250 mm and 90 g). Length at maturity was estimated to be 188 and 199 mm LT for males and females. Uterine fecundity ranged from one to four embryos (mean ± s.d.: 1·85 ± 0·45). Size at birth was estimated to be 105 mm LT . Gestation lasted between 4 and 5 months. The reproductive cycle of U. microphthalmum is hypothesized to be asynchronous and biannual.