Intra-annual variability of male migratory behavior associated with sperm quality in Lake Sturgeon

Abstract

Males exhibit variable pre-spawning behavior in response to environmental variables intra-sexual and inter-sexual interactions. Timing and duration of breeding area occupancy and access to mates may not alone be predictive of male reproductive success because of effects of intra- and inter-sexual interactions on sperm depletion and quality? For long-lived iteroparous species such as Lake Sturgeon (Acipenser fulvescens) that migrate to spawning areas, reproductive effort in a given year may affect inter-annual spawning interval and life-time reproductive success. To characterize measures of intra-annual male reproductive behaviors and trade-offs for lake sturgeon (e.g., inter-annual spawning interval), radio frequency identification (RFID) antennas were placed at the mouth of the Upper Black River, MI and immediately below upstream spawning locations to quantify river residence time, upstream migration time, number of intra-annual spawning migrations, annual spawning duration, and inter-annual spawning interval. Sperm samples collected from 180 males in 2017 and 2018 were used to quantify sperm concentration (sperm / mL). Computer assisted sperm analysis (CASA) was used to quantify measures of sperm quality in 2018. Analyses of variables associated with sperm concentration using combined 2017-2018 samples indicated river residence time had a strong negative influence on sperm concentration. River residence time was also negatively associated with principal components quantifying composite measures of sperm quality. The number of intra-annual spawning migrations and upstream migration time also were negatively associated with sperm quality. Male reproductive effort, quantified as the number of migratory events and rate of upstream migration, reduced sperm quality indicating sperm depletion is a reliable measure of sexual activity. Migratory behavior in the current year was associated with inter-annual spawning frequency, demonstrating trade-offs between benefits and costs associated with current reproductive effort that can affect future reproductive activity.

Full text


 !"#!$!%&'! (
")*!+&,-!./!%!.01120!/&
.",-.3)-4!011++-!.3!.01566!/&
Methods
•+2789:;98<
2781:;875<4/'-:)8<
•44,

•+&&:2781<
•:)2<
•.:44:<!
4!:<!4:<!
4=4<-)"
•278927814:2781<
4:<-:>68<:?<
&4..,:8028<
Introducon
•.=!@
=44
•(44
!44
A=44
•):Acipenser fulvescens<!
4AA
44
Objecves
8 B44
4
2 "AA
4A
Results
•427812789!4
27892781:)6<
•C8:D701E<2:>789E<?
4:)2<
•)=42789
27892781:)>0<
•-4C+8C+2!4
:)9<
•-44:)
D<
Conclusions
•.!
44
•F4
4
•)=2789
27812789!G=
4
•F
4A4

•)27892781
44
A44

Acknowledgments
(A278D2781'--
)(H'*
IAF4!"!-!-$!
*(?.",-
)(
2789 2781
7
677
8777
8677
2777
2677
>777
>677
0777
0677
7
67
877
867
277
267
>77
>67
077
067
--(+4
+4 -
+4:87DJ<
--(:$<
)DK,44:<
4:LJ<27892781877
)9K-4:<:C+8C+2<
2781877
)2KC

)8K/
'-
)6K.4427892781
2017 2018 Combined
0
20
40
60
80
100
120
140
160
180 1 Migration
2 Migrations
3+ Migrations
Spawning Year
Female Exposures (# of Females)
a
a,b
b
d
d,e
e
ccc
2017 2018 Combined
0
20
40
60
80
100
120
140
160 Short Stay
Long Stay
Spawning Year
Female Exposure (# of Females)
a
a
c
d
e
)0K.=44
:M<
)>K.=4
4
b