281 
National Marine 
Fisheries Service 
NOAA 
Fishery Bulletin 
established in 1881 -<?. 
Spencer F. Baird 
First U S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Movement and mortality of Atlantic salmon 
kelts {Solmo solar) released into the 
Penobscot River, Maine 
Email address for contact author: galphonsemaynard@gmail.com 
1 Department of Wildlife, Fisheries, and Conservation Biology 
University of Maine 
5755 Nutting Hall, Room 210 
Orono, Maine 04469-5755 
Present address for contact author: Cape Cod Commercial Fishermen's Alliance 
1566 Main Street 
Chatham, Massachusetts 02633 
2 U S. Geological Survey 
Maine Cooperative Fish and Wildlife Research Unit 
5755 Nutting Hall, Room 210 
University of Maine 
Orono, Maine 04469-5755 
Abstract— -The Penobscot River is 
home to the last remaining major 
run of Atlantic salmon (Salmo so¬ 
lar) in the United States and the 
subject of a century-long stocking 
effort. Since the 1970s, most kelts 
have been released to the estuary 
after they spawn in a hatchery, and 
the iteroparous share of the run has 
declined to <1%. We tagged with a 
radio transmitter 55 kelts that had 
spawned at a hatchery in 2015, and 
released them at two locations (head 
of tide and -50 km upstream) to as¬ 
sess 1) when kelts leave the river, 
2) whether release location influ¬ 
ences the timing of river exit, and 
3) whether kelts from the upper 
river could outmigrate through the 
hydroelectric complex of the river. 
The kelts were tracked from No¬ 
vember 2015 to July 2016. Although 
fish from both release groups left 
the system within one month, the 
majority (84%) overwintered in 
freshwater. Many (71%) kelts that 
overwintered in freshwater made 
upstream movements in November 
and December. There was no differ¬ 
ence in upstream movement rates, 
timing of outmigration, or survival 
between the release groups. Survival 
to outmigration was 23.6%. This low 
survival to outmigration may have 
contributed to the precipitous de¬ 
cline in iteroparous Atlantic salmon 
from the Penobscot River over the 
last four decades. 
Manuscript submitted 8 March 2018. 
Manuscript accepted 28 June 2018. 
Fish. Bull. 116:281-290 (2018). 
Online publication date: 20 July 2018. 
doi: 10.7755/FB. 116.3-4.6 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
George A. Maynard (contact author) 1 
Lisa K Izzo 1 
Joseph D. Zydlewski 1 - 2 
Atlantic salmon (Salmo salar ) popu¬ 
lations in the United States have de¬ 
clined precipitously over the last sev¬ 
eral decades, and the only remain¬ 
ing population segment is listed as 
endangered under the U.S. Endan¬ 
gered Species Act (Fay et al., 2006). 
The Penobscot River historically sup¬ 
ported spawning runs of more than 
100,000 individuals (Saunders et 
al., 2006), but recent returns have 
averaged only around 1000 fish an¬ 
nually (Cox 1 ). The U.S. Government 
has identified restoration of the dis¬ 
tinct population segment of the Gulf 
of Maine as a high priority (NMFS 
and USFWS, 2005). However, Atlan¬ 
tic salmon face a variety of threats 
because of their anadromous and 
iteroparous life history (Legault, 
2005; Maynard et al., 2017), such as 
overfishing, pollution, and the pres¬ 
ence of dams (Parrish et al., 1998; 
1 Cox, O. 2016. Personal commun. 
Maine Dep. Mar. Resour., 21 State House 
Station, Augusta, ME 04333-0021. 
Nieland et al., 2015). Although many 
stages of Atlantic salmon life history 
have been well studied (Klemetsen 
et al., 2003), comparatively little is 
known about the survival and move¬ 
ments of kelts (postspawning adults) 
after successful spawning. Because 
repeat spawners have increased re¬ 
productive influence in salmonine 
populations (Kusterle et al., 2013; 
Trammell et al., 2016), ensuring sur¬ 
vival of kelts could enhance restora¬ 
tion efforts. 
Many anadromous salmonines can 
spawn multiple times during their 
life cycle, returning to sea after each 
spawning event to recondition (Kl¬ 
emetsen et al., 2003). Survival af¬ 
ter spawning can be high in Atlan¬ 
tic salmon (-80%; Chadwick et al., 
1978; Jonsson et al., 1990). However, 
a much smaller proportion of fish 
survive to spawn again (Ducharme, 
1969). Broadly, the outmigration of 
kelts takes place in two stages. A 
small proportion of individuals mi¬ 
grate directly to the sea, whereas the 
