Paddlefish: Ecological, Aquacultural, and Regulatory Challenges of Managing a Global Resource

<i>Abstract</i>.—In this chapter we outline and update Missouri’s Paddlefish (<i>Polyodon spathula</i>) experience, including efforts to culture the species and the use of those fish in its fishery management program for reservoirs. The Osage River, historically one of the nation’s premier Paddlefish rivers, underwent major habitat alterations in the twentieth century, including the construction of two major mainstem reservoirs (Lake of the Ozarks and Harry S. Truman Lake), resulting in the loss of nearly all natural spawning habitat for the Paddlefish. In response, the Missouri Department of Conservation (MDC) began a program of artificial propagation for the species at Blind Pony Hatchery (BPH) in the 1960s. Early propagation developments in Missouri and elsewhere included research on early life history, feeding, and improving growth rates. In the early 1970s, the MDC determined that a Paddlefish population could be established in Table Rock Lake and supplementation could build and maintain harvestable populations in Lake of the Ozarks and Harry S. Truman Lake. As of 2019, these three reservoirs support quality Paddlefish fisheries and are known globally for their harvest potential. Even though Paddlefish propagation in Missouri has been fruitful, additional efforts through collaboration with other entities and states are underway to continually improve success. Through collaboration, unique intricacies in culture and stocking techniques have surfaced that should be implemented as propagation and restoration programs commence around the world. To this end, Paddlefish propagation has been successful and will continue to play a role in restoring, maintaining, or creating Paddlefish fisheries.

2019 ◽  
Vol 70 (12) ◽  
pp. 1659 ◽  
Author(s):  
Troy A. Rogers ◽  
Anthony J. Fowler ◽  
Michael A. Steer ◽  
Bronwyn M. Gillanders

Understanding the early life history processes of fish that lead to recruitment is critical for understanding population dynamics. This study explored the early life history of King George whiting (Sillaginodes punctatus) that recruited to an important nursery area in South Australia in 2016 and 2017. The early life history was reconstructed based on the retrospective analysis of otolith microstructure and chemistry for settlement-stage larvae collected fortnightly from July to November. These fish hatched between March and July, but a 3-week period in May led to 52–71% of recruitment. Recruits from successive sampling occasions differed in age, size and growth rate, potentially related to seasonal changes in water temperature and larval food availability. During both years, there were significant changes in otolith elemental chemistry among the groups of recruits that primarily related to changes in Sr:Ca. There are two hypotheses to account for the differences in otolith chemistry: either (1) a single, primary spawning source and within-season environmental change; or (2) multiple spawning sources. Further investigation with oceanographic models of larval dispersal will help differentiate between these. The retrospective analysis of otoliths has improved the understanding of early life history for this important species, with implications for fishery management.


<em>Abstract</em>.—Surveys undertaken in 2003 and 2005 have increased our knowledge of the distribution of roundnose grenadier <em>Coryphaenoides rupestris </em>in the North Atlantic. The data suggest a wide distribution of young grenadier in the high seas and support previous assumptions about long passive migrations of this species at early life-history stages.


2020 ◽  
Vol 650 ◽  
pp. 7-18 ◽  
Author(s):  
HW Fennie ◽  
S Sponaugle ◽  
EA Daly ◽  
RD Brodeur

Predation is a major source of mortality in the early life stages of fishes and a driving force in shaping fish populations. Theoretical, modeling, and laboratory studies have generated hypotheses that larval fish size, age, growth rate, and development rate affect their susceptibility to predation. Empirical data on predator selection in the wild are challenging to obtain, and most selective mortality studies must repeatedly sample populations of survivors to indirectly examine survivorship. While valuable on a population scale, these approaches can obscure selection by particular predators. In May 2018, along the coast of Washington, USA, we simultaneously collected juvenile quillback rockfish Sebastes maliger from both the environment and the stomachs of juvenile coho salmon Oncorhynchus kisutch. We used otolith microstructure analysis to examine whether juvenile coho salmon were age-, size-, and/or growth-selective predators of juvenile quillback rockfish. Our results indicate that juvenile rockfish consumed by salmon were significantly smaller, slower growing at capture, and younger than surviving (unconsumed) juvenile rockfish, providing direct evidence that juvenile coho salmon are selective predators on juvenile quillback rockfish. These differences in early life history traits between consumed and surviving rockfish are related to timing of parturition and the environmental conditions larval rockfish experienced, suggesting that maternal effects may substantially influence survival at this stage. Our results demonstrate that variability in timing of parturition and sea surface temperature leads to tradeoffs in early life history traits between growth in the larval stage and survival when encountering predators in the pelagic juvenile stage.


2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Daniel E Winkler ◽  
Michelle Yu-Chan Lin ◽  
José Delgadillo ◽  
Kenneth J Chapin ◽  
Travis E Huxman

We studied how a rare, endemic alpine cushion plant responds to the interactive effects of warming and drought. Overall, we found that both drought and warming negatively influenced the species growth but that existing levels of phenotypic variation may be enough to at least temporarily buffer populations.


2017 ◽  
Vol 36 (2) ◽  
pp. 338-350 ◽  
Author(s):  
John M. McLeod ◽  
Howard L. Jelks ◽  
Sandra Pursifull ◽  
Nathan A. Johnson

Crustaceana ◽  
1994 ◽  
Vol 66 (3) ◽  
pp. 271-294 ◽  
Author(s):  
Bruce F. Phillips ◽  
John D. Booth

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