51813_Sturgeon biodioversity an.PDF

Environmental Biology of Fishes 48:399–405. 1997.
© 1997 KluwerAcademicPublishers.Printed in theNetherlands

SensitivityofNorth American sturgeons and paddlefish to fishing mortality

JohnBoreman
UMass/NOAA Cooperative Marine Education and Research Program, The EnvironmentalInstitute, Blaisdell
House, University of Massachusetts, P O. Box 30820, Amherst MA 01003–0820, U. .S.A.

Received 6.10.1994 Accepted 28.3.1996

Keywords: reproductive potential, exploitation, endangered species, chondrosteans, eggs per recruit

Synopsis

Sturgeons andpaddlefishexhibitunusualcombinations of morphology,habits, andlifehistory characteristics,

whichmake themhighlyvulnerable to impacts fromhumanactivities,particularlyfisheries. FiveNorthAmer-

icansturgeons (shortnose,Gulfpallid,Alabama, and green sturgeon) arelisted asendangered orthreatened

by management authorities.Managers haveinstitutedfisheryclosures for thethreeotherspecies ofNorth

American sturgeons (Atlantic,white. andshovelnose) and paddlefish because of low stockabundance at

some point inthiscentury.Reproductive potential in fourspecies 1examined(Atlantic,white, andshortnose

sturgeon, andpaddlefish) is moresensitive to fishingmortalitythan it is forthree otherintensively-fished

coastalspecies inNorthAmerica: stripedbass.winterflounder, andbluefish. Thesturgeons andpaddlefish

are generallylonger-livedthan thethree othercoastal species, and alsohave anolder age atfullmaturity,

lowermaximumfecundityvalues, andolderages atwhich 50% of thelifetime eggproduction isrealizedwith

no fishing mortality.

Introduction sturgeon, and shovelnose sturgeon); (2) adults

move into brackish water (white sturgeon and

Of the 25 chondrosteanspecies stillliving in the shortnosesturgeon); or (3)adultsmoveinto the

NorthernHemisphere. thepaddlefish, Polyodon ocean(whitesturgeon,greensturgeon. andAtlan-

spathulaand eightspecies ofsturgeon arefound in tic sturgeon). All of thespeciesreproduce infresh

North American waters (Birstein 1993): Atlantic water.

sturgeon,Acipenser oxyrinchus, shortnose stur- Sturgeons and paddlefish exhibit unusual combi-

geon,Acipenserbrevirostrum,whitesturgeon,Aci- nations of morphology,habits, andlifehistory char-

penser transmontanuslake sturgeon,Acipenser ful- acteristics,whichmakethemhighlyvulnerable to

vescens,greensturgeon,Acipensermedirostrispal- impactsfromhumanactivities,particularlyfisher-

lid sturgeonScaphirhynchusalbusshovelnose stur- ies. InNorth America, humanactivitiesknown to

geonScaphirhynchusplatorynchusand Alabama impactsturgeons andpaddlefish areindustrial and

sturgeon,Scaphirhynchussuttkusi They inhabit municipalpollution, blockage ofaccess tohabitats

fresh,brackish, andsea watersystems inNorth bydikes and dams, channelization and elimination

America. andexhibitthreetypes oflifehistory pat- of backwaterareas, dewatering of streams,physical

terns (after Rochard et al.1990): (1)their entirelife destruction of spawning grounds, inundation of

history isspent infreshwater(paddlefish,lake stur- habitat byreservoirs, andoverfishing(Baker1980,

geon,white sturgeon,pallidsturgeon,Alabama Carlson &Bonislawsky1981,Trautman1981,Beck-