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Reproductive environment of the decreasing Indian river shad in Asian inland waters: disentangling the climate change and indiscriminative fishing threats.

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Title Reproductive environment of the decreasing Indian river shad in Asian inland waters: disentangling the climate change and indiscriminative fishing threats.
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Creator Sarkar UK, Roy K, Karnatak G, Naskar M, Puthiyottil M, Baksi S, Lianthuamluaia L, Kumari S, Ghosh BD and Das BK
 
Subject Asian inland
 
Description Not Available
The regional climate has significantly warmed with erratically declining annual rainfall and intensified downpour within a narrower span of monsoon months, which led to an increased trophic state (≈algae) in most inland waters. Freshwater clupeids vitally control the aquatic food chain by grazing on algae. Despite increasing food availability, IUCN Red List® revealed 16 freshwater clupeids with a decreasing population trend. We investigated one such species' reproductive dependencies, Gudusia chapra (Indian river shad), in the lower Gangetic drainage (India) under a mixed context of climate change and overfishing. Monthly rainfall (≥ 60-100 mm) and water temperature (≥ 31-32 °C) are key breeding cues for females. The regional climate seems inclined to fulfill these through the significant part of the breeding season, and indeed the species has maintained consistent breeding phenology over 20 years. Other breeding thresholds relevant to fishing include size at first maturity (≥ 6.8 cm; reduced by ~ 25-36%) and pre-spawning girth (Girthspawn50 ≥ 7 cm; first record). Girthspawn50 is a proxy of the minimum mesh size requirement of fishing nets to allow safe passage of "gravid" females ( + 22% bulged abdomen) and breed. The operational fishing nets (3-10 cm mesh) probably have been indulged in indiscriminative fishing of gravid females for generations. Under a favorably changing climate and food availability, existing evidence suggests a fishery-induced evolution in regional females (to circumvent such mesh sizes) through earlier maturation/puberty at smaller sizes. It could be an early warning sign of population collapse (smaller females → lessening fecundity → fewer offspring). Overfishing seemed to be a bigger threat than climate change.
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Date 2022-07-04T04:30:58Z
2022-07-04T04:30:58Z
2021-01-01
 
Type Research Paper
 
Identifier Not Available
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http://krishi.icar.gov.in/jspui/handle/123456789/73556
 
Language English
 
Relation Not Available;
 
Publisher Not Available