the resilience of southeast alaska fisheries in changing ......1 title: resilience of southeast...
Post on 12-Oct-2020
5 Views
Preview:
TRANSCRIPT
The Resilience of Southeast Alaska Fisheries in Changing Waters
Captain: Corbin Mitchell
Siena Hanna
Zoey Kriegmont
Ryan Moritz
McLain Sidmore
Pier Pressure
JuneauDouglas High School
10014 Crazy Horse Drive Juneau, AK 99801
Primary contact: Corbin Mitchell
corbinm72@gmail.com
Coach: Benjamin Carney
benjamin.carney@juneauschools.org
“This paper was written as part of the Alaska Ocean Sciences Bowl high school competition.
The conclusions in this report are solely those of the student authors.”
The Resilience of Southeast Alaska Fisheries in Changing Waters
With the changing climate in Southeast Alaska (SE AK), we have recently seen an influx in the
populations of walleye pollock (Theragra chalcogramma ), and magistrate armhook squid (Berryteuthis
magister). SE AK is currently home to a number of extremely profitable salmon fisheries, on which
communities rely for their economic success. While no studies have been done on the effects these
species may have on current salmon fisheries, we will attempt to examine parallels in diet to determine
possible outcomes of the inflated populations of pollock and squid on the fisheries. Additionally, we will
explore how interspecific competition will affect the major species of salmon in SE AK including chum
(Oncorhynchus keta ), pink (Oncorhynchus gorbuscha), and sockeye (Oncorhynchus kisutch ). We will
also explore how possible outcomes may affect the resilience of local ecosystems, as well as the
resilience of SE AK communities, and will suggest possible methods of management for the changing
fisheries. For instance, we will suggest that pollock and squid industries could prove an effective
management tool for population control of these species in SE AK. Profitable pollock industries exist in
the Bering Sea and the introduction of such a fishery in SE AK could prove beneficial for both the
ecosystem and the local economies. We will attempt to address the major considerations for both the
environment and the economic future of SE AK with a hope of fostering greater interest and research
into the topic.
1
Title: Resilience of Southeast Alaska Fisheries in Changing Waters
I. Introduction
As climate change has caused the world temperature levels to increase, ocean waters have
become warmer. The current El Niño, with JuneAugust sea surface temperature averaging about 1.22
degrees Celsius above normal (Becker, 2015), may be exacerbating these changes. This shift in
temperature could cause enormous shifts in the Southeast Alaska (SE AK) ecosystem which, in turn,
would have enormous effects on the socioeconomic future of SE AK. In the instance of Southeast
Alaska’s coastal areas, walleye pollock (Theragra chalcogramma ) and magistrate armhook squid
(Berryteuthis magister) have been appearing in greater numbers.
These changes in the populations of pollock and squid imply shifts in the ecosystem, and could
include shifts in the dynamics of competition between species, such as pollock and salmon. If
interspecific competition did increase, there could be declines of organisms of lower trophic levels due to
increased predation. The food web may be altered with the increasing populations of pollock and squid
in the marine environment of SE AK, and the salmon populations may decrease as result.
The Bering Sea pollock fishery is the largest fishery in Alaska and the United States. SE AK
pollock are increasing in number and this may represent an economic opportunity; the extent to which is
uncertain due to the number of possible scenarios that could result from shifting interspecific
relationships.
An infant squid fishery is currently emerging in Southern SE AK. Squid have proven to be a
profitable resource for harvest in other regions of the country. California has a market squid fishery that
is one of the largest commercial fisheries in that state. Fishermen employ seine and brail gear to capture
the squid. The populations have been effectively managed by the California Department of Fish and
2
Wildlife (California Department of Fish and Wildlife, 2015). The squid fishery in SE AK is at present very
small. Only three permits have been issued for harvest and there are no processors, at present, buying
squid in SE AK. We assume that the squid is being used as bait for other fisheries by the harvesters, or
is being sold to sports fishermen as bait.
Despite any other fisheries that could potentially be introduced in SE AK, the salmon fisheries
remain at the core of the local economy. Any change in the ecosystem could negatively affect this
resource which would have disastrous results on the socioeconomic future of fishing communities in SE
AK. The consideration and
management of any
additional fisheries
introduced in the region must
be initiated with the salmon
industry in mind, and
decisions on potential
industries will be made in the
interest of protecting local
salmon fisheries with the
goal of protecting
socioeconomic impacts on
SE AK.
In this paper, we will explore
some of the ecological and socioeconomic effects that these increasing populations of squid and pollock
3
may pose in SE AK. We will analyze possible shifts in populations and discuss how management of the
species must adapt. We will also focus on the possible impacts on, and the resilience of, the coastal
fisheries that may be impacted and the coastal communities that rely on fishing for their primary income
and would be affected by any changes in the current salmon fisheries.
II. Ecosystem
The Gulf of Alaska, including SE AK waters (Figure 1), encompasses the convergence zone of
the North American and Pacific plates, making it a tectonically active area. Many of the geographical
features of SE AK are results of tectonic or seismic activity and tend to change as result of landslides,
faulting, and other factors. Furthermore, SE AK’s continental shelf has many submarine troughs and
banks that facilitate exchange of water between the Gulf of Alaska and the internal waters of SE AK
itself (Weingartner, et al. 2009).
Clarence and Chatham Strait are some of the most significant channels that penetrate SE AK,
in that they connect to many of SE AK other waterways (Figure 1) and, are important to tidal water flow.
Geographically, Clarence Strait is a waterway 240 km long and attaches the interior waters of SE AK to
Dixon Entrance. Similarly, Chatham Strait is 240 km long, but it encompasses areas between the
Baranof and Chichagof islands and Admiralty island. There are several other channels that permeate
SE AK, including, from north to south, Lynn Canal, Icy Strait, and Frederick Sound. These waterways
serve as mixing areas for stream runoff and funnel the winds that mix the water. (Figure 1)
A variety of factors, including proximity to shores, glaciers, estuaries, river mouths, and the
continental shelf, as well as tidal features, nutrient availability, and water depth cause the ecology of SE
4
AK to vary greatly depending on location. This diversity of marine habitats supports a rich ecosystem
and provides a foundation for numerous fisheries to exist.
Generally, though, during spring, when stratification and levels of light allow, the major
phytoplankton bloom occurs throughout SE AK. It initiates in the internal waters and spreads outwards
towards the shelf. Euphausiids and copepods consume zooplankton, whose populations tend to peak in
May or June (Weingartner, et al. 2009). These organisms are the primary food sources for animals of
higher trophic levels, including all salmon species and walleye pollock (Groot and Margolis, 1991).
III. Biology of Species Concerned
The general biology and life cycles of salmon, pollock, and squid is well known; and we will,
therefore, refrain from including this general information. Instead, we will focus on the diets of each
species and the overlaps between them.
Squid: About fifteen species of squid have been identified in the Eastern Bering Sea. Much less
known about those in the Gulf of Alaska and SE AK, but it is speculated that the species in all three
regions may be similar, though more temperate species may also be present in SE AK (Ormseth, 2011).
Of these, the magistrate armhook squid is identified as the most commercially important squid in the
North Pacific area (Ormseth, 2011). Because of its comparatively greater commercial importance,
magistrate armhook squid will be the primary species discussed, though it is not the only species of
squid present in SE AK or the Gulf of Alaska (Ormseth, 2011). A sampling of 338 armhook squids, in the
northeast Pacific Ocean, in May of 1999, found a range in with mantle lengths from 10.3 to 103.2 mm.
The sampling revealed that their diets are made up of seven major groups: copepods, chaetognaths,
amphipods, euphausiids, ostracods, various fish, and various gelatinous organisms. Copepods were the
5
most abundant prey making up more than 50% of the mass of the total diet, followed by amphipods
which made up 5% of the mass of the total diet. (Uchikawa, 2004).
Pollock : Less is known about the walleye pollock population in the Gulf of Alaska than is known
about that in the Bering Sea, as the pollock fishery in the Bering Sea is of greater economic importance.
Still, in the Gulf of Alaska, the second largest biomass of groundfish is made up of pollock (Adams, et al.
2007). Walleye pollock reach lengths of up to 100 centimeters over their lifespan of up to 17 years. They
begin to spawn and reproduce at the ages of 3 to 4 (NOAA, 2009). During their first years of life, juvenile
pollock primarily consume euphausiids, in addition to larval and adult copepods, small fish, and
mollusks. Adult pollock heavily rely on euphausiids, in addition to copepods, shrimp, other bony fish,
mollusks (Cargnelli, 1999). Pollock are also reported to feed on younger pollock though the amount of
cannibalism present in the walleye pollock population of the Gulf of Alaska is less than that of the Bering
Sea (Adams, et al. 2007). Predators of pollock in the Gulf of Alaska include Steller sea lions, common
murres, harbor seals, arrowtooth flounder, Pacific cod, Pacific halibut, sablefish, and larger pollock
(Adams, et al. 2007).
Salmon: Over the course of their lifetimes, salmon (Genus Oncorhynchus ) consume hyperiid
amphipods, other small fish, juvenile squid, euphausiids, copepods, and pteropods, though there are
variations in their diets specific to different species of salmon (Davis, 2005). Chum salmon (O. keta )
primarily consume euphausiids, hyperiid amphipods, small fish, copepods, squid, and squid larvae. Pink
salmon (O. gorbuscha) diets are primarily made up of euphausiids, amphipods, copepods and crab
megalopa. Sockeye (O. kisutch ) diets consist primarily of euphausiids, hyperiid amphipods, copepods,
small fish, and squid. Coho salmon diets are made up of 34.6% small fish, 26.7% amphipods, and
26.2% crab megalops. Chinook salmon (O. tshawytscha ) diets are primarily made up of herring, pelagic
6
amphipods and crab megalopa, which collectively account for 70%92% of their diets (Groot and
Margolis, 1991).
IV. Interspecies Competition
Squid make up a large component of the diets of Pacific salmon, and are an especially large
source of food during years of low zooplankton populations (Kaeriyama, 2000). With an increase in the
population of armhook squid in SE AK, the possibility arises that salmon species could become
increasingly dependent on squid, thus decreasing reliance on euphausiids, amphipods, and copepods.
Though we were unable to locate any specific studies centered on interspecific competition
between pollock, salmon, and squid, there are noticeable dietary overlaps. We recommend that there be
studies done in SE AK on the
interspecific competition
between pollock, squid, and all
species of salmon in order to
further our understanding of the
exact extent to which salmon,
pollock and squid compete for
resources and, therefore, our
understanding of possible
effects this
competition may have
on the SE AK marine
7
ecosystem. For now, we will draw parallels between the diets of salmon and pollock in order to illustrate
possible sources of competition.
Chum, pink, and sockeye salmon are the species most likely to experience interspecies
competition with pollock and squid. The overlap in the diets of pollock, squid and these species of
salmon is immense due to the fact that the diets are all comprised primarily of small prey such as
zooplankton, crustaceans, and copepods. The most significant of these overlaps in prey are
euphausiids, which are one of the primary sources of prey for pollock, and all three species of salmon,
as well as a minor prey source for squid (Kaeriyama, 2000; Uchikawa, 2004). Dietary overlap between
squid and salmon is heavily centered around copepods, as copepods compose the majority of the diet
of armhook squid (Uchikawa, 2004). Other species of zooplankton compose the diets of the pollock and
the salmon species in question (Kaeriyama, 2000).
V. Southeast Alaska Fisheries
Current SE AK salmon fisheries differ greatly by species. The species with which we are
primarily concerned are the chum, pink, and sockeye salmon that spend a relatively large portion of their
lives in estuary environments. Chums are generally harvested by purse seine net and gillnet, pinks are
harvested using purse seine, and sockeyes are harvested using gillnets. Both salmon and pollock tend
to reside in the same estuary environments. It is, therefore, likely that the impact of an influx of pollock
will be far more visible with regard to these species than the chinook and coho salmon which spend a
greater portion of their lives in the open ocean. The sheer number of chum and pink salmon harvested
denote their overall economic importance to the fisheries of SE AK to be far greater than chinook and
coho which, while valuable, are harvested in fewer numbers (Table 1).
8
While it is, as of yet, unclear what the effects of increasing pollock numbers will have on the
existing salmon industries, we envision three possible outcomes. The first would be that with rising
numbers in pollock, the salmon population would be unaffected. This overall gain in the number of
commercially valuable fish would result in an economic gain for the SE AK fishing communities. The
second would be that as pollock populations rise there would be increased interspecific competition
resulting in a decrease in the chum, pink and sockeye populations. This loss of salmon would pose a
large negative impact on the socioeconomic climate of many SE AK communities; primarily affecting
gillnetters and trollers, though a potential purse seiner pollock fishery could benefit. The third would be
that with a rising pollock population, the amount of nutrients that both salmon and pollock are dependent
on would decrease, causing both the salmon and pollock populations decrease until they reach an
equilibrium. In this scenario, the reduction in profits from the salmon fisheries would be mitigated by the
profits from a new pollock fishery and there would be no economic benefit, nor a substantial loss for SE
AK communities.
Management of current fisheries in areas where pollock and squid are present may have to be
altered to meet the Alaska constitutional requirements for sustainable management. This includes the
development of management plans for new fisheries for pollock and squid. This would also require due
diligence on the part of the current management plan for SE AK salmon fisheries so as to be responsive
to changes in populations. Should the increasing numbers of pollock and squid in SE AK negatively
affect the populations of salmon, more conservative management of salmon fisheries may become
9
necessary to ensure the continued survival of the industry in SE AK. .
Current Alaskan Pollock fishery : There are currently two pollock fisheries in Alaska; one in
the Eastern Bering Sea and Aleutian Islands and a smaller fishery located in the Gulf of Alaska. In 2012,
the harvest in the Eastern Bering Sea fishery totaled 1,206,400 metric tons, while in the Gulf of Alaska,
the catch totaled 104,000 metric tons of pollock (Fissel, 2013 ). The fishing method currently practiced by
these fisheries is the pelagic trawl. The major markets for the pollock caught in Alaska consist of Japan,
the U.S., and Europe (Marine Stewardship Council, 2015).
In an interview with Scott Kelley on November 11, 2015, we discovered that there have been
two pollock permits issued in SE AK, and due to the fact that trawling is illegal east of 140 degrees west
longitude, with the exception of a small state waters beam trawl flatfish fishery near Petersburg, they are
purse seining permits. The permits require the boats to have an observer from the department of fish
and game on board their vessel while they are fishing for pollock. Currently neither of the boats have
begun to fish for pollock in SE AK (Kelley personal communication, 2015).
VI. Resilience
Resilience in SE AK can be broken into two equally important facets; the resilience of the
ecosystem and the socioeconomic impacts on the resilience of SE AK communities. Resilience of an
10
ecosystem refers to the ability of that ecosystem to resist change and to recover from a disturbance
within the environment as well as the amount of time that is required for a full restoration. It is, as of yet,
unclear what the impacts of an increase of pollock and squid will be on the food web, but it is likely that
interspecific competition between salmon and increasing pollock and squid over an indefinite period of
time will affect the resilience of the SE AK ecosystem. Another consideration is the resilience of SE AK
communities reliant on the salmon fisheries should these be greatly affected by the influx of pollock and
squid species in the region. Salmon is a hugely valuable economic resource within the SE AK economy
and the potential decline of this fishery could have disastrous effects on the area. The effects of this
loss, should they occur, could potentially be mitigated by the instigation of a pollock fishery in SE AK
and the introduction of a squid bait fishery that would reduce the cost of bait currently being imported
from California squid fisheries. While we are currently unable to quantify the potential economic benefits
from the emerging squid fishery and a potential pollock fishery, it is likely that profits from these
emerging industries would help the resilience of the SE AK economy, providing jobs for fisherman and a
diversification in the production of seafood in communities across the SE AK. Responsible management
in these fisheries for the purpose of controlling the populations of pollock and squid could also create a
means of lessening interspecific competition and ensuring the continued success of both the existing
salmon fisheries and the potential pollock and squid fisheries. Such measures might immeasurably
increase the resilience of both the SE AK ecosystem, and the socioeconomic security of the region.
VII. Addressing the Resilience of Fisheries in Southeast Alaska
Sustainability of the salmon population, and, likewise, the socioeconomic implications that are
related, are paramount to the resilience of SE AK Communities, as fishing is one of the primary sources
11
of income in the region (along with tourism). The vast majority of economic value that is gained from
fishing in the region currently comes from wild Alaskan salmon.
The Alaskan salmon fishery is one of the last sustainable salmon fisheries in the world. The
Alaska Department of Fish and Game is noted for its very effective management of the wild Alaskan
salmon population, allowing the continuation of sustainable yields. They have worked to emphasize the
importance of protecting the resilience of the ecosystem, especially near spawning grounds for salmon
to ensure that the salmon fisheries will continue in the future. We do, however, believe that the
Department of Fish and Game ought to be aware of, and take into account, a rising population of pollock
and squid in SE AK waters when deciding on a management plan for local fisheries. We believe that this
factor could have a large impact on the management tactics that the Department of Fish and Game may
need to implement in order to continue to achieve a sustainable yield of salmon.
The reintroduction of sea otters in SE AK exemplified what can happen when a predator's
population drastically increases. In the case of sea otters, the population had once been a part of the SE
AK ecosystem but had been nearly eradicated by Russian fur hunters before the introduction of dive
fisheries management in Alaska. The reintroduction of sea otters into SE AK has caused huge changes
in the ecosystem. As the otter population began to rebound between the 1960s and the 1980s, huge
declines were seen in the dive fisheries in SE AK. All fishing for sea urchins had to be halted in Sitka
Sound due to reduced populations and the sea cucumber, geoduck clam, and abalone fisheries were all
severely diminished by the upsurge in sea otter numbers (Pritchett et al, 2008). To avoid a similar
situation, in which pollock and salmon do exhibit interspecific competition, we believe that close
attention ought to be payed to the increase of the pollock and squid populations and management to
control them should be implemented by the Department of Fish and Game. The opening of fisheries for
12
pollock and an expansion of the squid fishery could provide a method of managing interspecific
competition in SE AK waters as well as offering new employment opportunities for fishermen in SE AK.
In conjunction with the management of salmon, there must be consideration for the
management of pollock should new fisheries be implemented. Not only would a walleye pollock fishery
allow for the management of the pollock population, but it would also increase the socioeconomic
resilience of the fisheries of SE AK by providing an additional source of income to the communities of
the region. With a rising number of squid, a squid fishery would serve a similar purpose, by helping to
increase the economic resilience of the communities. Three permits have been issued thus far to
fishermen for the harvest of squid in SE AK. Currently fishermen have been jigging squid outside of
Ketchikan; however, we were unable to find a processor anywhere in SE AK that has been purchasing
the squid from these fishermen (Kelley personal communication, 2015). This likely indicates that the
fishermen are using the squid as bait, or selling the squid to sport fishermen for the same purpose.
VIII. Conclusion
We believe that, while interspecific competition between pollock, squid, and salmon is
certainly an important issue for SE AK with huge implications, there is simply not enough research
completed on the subject for fisheries managers to make an informed decision on the subject. We
suggest that research on the interspecific competition between the three salmon species in question,
pollock and squid be conducted in SE AK to determine the effects of the influx these new species may
have on existing salmon fisheries. In addition, population surveys will need to be done on both pollock
and squid to determine the rate at which populations are increasing as well as the viability of the
introduction of fisheries for these species.
13
We would also suggest that should decreases in the return of salmon be seen in the
coming years that the Department of Fish and Game should consider the possible effects of increasing
pollock and squid populations and proceed to proactively manage species accordingly. More
conservative management of salmon resources in SE AK may prove necessary to continue the
availability of the salmon resource and to ensure socioeconomic resilience of SE AK communities.
Additionally, we would suggest that the possible instigation of a squid bait fishery could mitigate
negative effects of squid on the salmon fisheries. The introduction of this fishery would provide
additional income for fishermen and processors, and would reduce the cost of bait that previously had to
be imported from California fisheries, therefore increasing the resilience of the fishing communities of
SE AK.
To determine the viability of a potential pollock industry in SE AK, we suggest that test fisheries
be established in areas with high pollock populations. The results from this survey could suggest areas
in which profitable fisheries could be established, as well as to give the Department of Fish and Game
an idea of the areas in which the population of pollock could prove detrimental to salmon fisheries.
References
Adams CF, Pinchuk AI, Coyle KO (2007) Seasonal changes in the diet composition and prey selection
of walleye pollock (Theragra chalcogramma) in the northern Gulf of Alaska. Fish Res
84:378−389
Alaska Commercial Salmon Harvest and Exvessel Values. (2015, October 1). Retrieved November 21,
2015. Alaska Pollock Bering Sea and Aleutian Islands. (2015, October 20). Retrieved
14
November 17, 2015, from
https://www.msc.org/trackafishery/fisheriesintheprogram/certified/pacific/bsaipollock
Alaska Pollock Gulf of Alaska. (2015, October 15). Retrieved November 17, 2015, from
https://www.msc.org/trackafishery/fisheriesintheprogram/certified/pacific/gulfofalaskapollo
ck
Becker, E. (2015, September 10). September 2015 El Niño Update and Q&A | NOAA Climate.gov.
Retrieved November 17, 2015, from
https://www.climate.gov/newsfeatures/blogs/enso/september2015elniñoupdateandqa
Cargnelli, L., Griesbach, S., Packer, D., Berrien, P., Johnson, D., & Morse, W. (1999). Pollock,
Pollachius virens, Life History and Habitat Characteristics. NOAA Technical Memorandum, NMFSNE131 (122152).
Davis, N., Fukuwaka, M., Armstrong, J., & Myers, K. (2005). Salmon Food Habits Studies in the Bering
Sea, 1960 to Present. NPAFC Technical Report, 6 , 2428.
‘"FBE Focal Species Walleye Pollock." FBE Species of Interest . NOAA, 27 Mar. 2009. Web. 14 Nov.
2015. <http://www.afsc.noaa.gov/race/behavioral/pollock_fbe.htm>.
Fissel B., Dalton M., Felthoven R., GarberYonts B., Haynie A., HimesCornell A., Kasperski S. Stock
assessment and fishery evaluation report for the groundfish fisheries of the Gulf of Alaska and
Bering Sea/Aleutian Islands area: economic status of the groundfish fisheries off Alaska,Fi
2013.
Groot, C. and L. Margolis. 1991. Pacific Salmon: Life Histories. Vancouver, BC: UBC Press. 564 pages.
Ka eriyama, M., M. Nakamura, M. Yamaguchi, H. Ueda, G. Anma, S. Takagi, K.Y. Aydin, R.V. Walker,
and K.W. Myers. 2000. Feeding ecology of sockeye and pink salmon in the Gulf of Alaska. N.
Pac. Anadr. Fish Comm. BUll. No.2: 5563.
Kelley, S. Personal interview. November 16, 2015.
15
Market Squid. (2015). Retrieved November 29, 2015, from
https://www.wildlife.ca.gov/Conservation/Marine/CPSHMS/MarketSquid
Ormseth, Olav A. "21. Assessment of the squid stock complex in the Bering Sea and Aleutian Islands."
NPFMC Bering Sea and Aleutian Islands SAFE.
Pritchett, M. and Z. Hoyt. 2008. Report to the Board of Fisheries, Miscellaneous Dive Fisheries.
Alaska Department of Fish and Game, Fishery Management Report No. 0863, Anchorage.
Uchikawa K, Bower JR, Sato Y, Sakurai Y (2004) Diet of the minimal armhook squid (Berryteuthis anonychus ) (Cephalopoda: Gonatidae) in the northeast Pacific during spring.Fishery Bulletin, 102, 733–739.
‘"Walleye pollock Theragra chalcogramma ." NOAA Fisheries Service Alaska Fisheries Science Center.
NOAA, 2010. Web. 14 Nov. 2015.
<http://www.afsc.noaa.gov/Education/factsheets/10_Wpoll_FS.pdf>.
Weingartner, T., Eisner, L., Eckert, G., & Danielson, S. (2009). Southeast Alaska: Oceanographic
habitats and linkages. Journal of Biogeography, 36 (3), 387400.
top related