Claire Corlett

Fish Food, Fish Tanks, and More
Genetics for Sustainability: Management of Bristol Bay Sockeye Salmon

Genetics for Sustainability: Management of Bristol Bay Sockeye Salmon


[MUSIC PLAYING] In Bristol Bay,
Alaska for a few weeks every summer an average of
38 million sockeye salmon emerge from the Pacific. This consistently large
return defines the communities of the region and has been
commercially harvested since the late 1800s. Today, the fishery is the
highest value salmon fishery in North America. Effective management is
crucial to the conservation of this highly
exploited species. Management biologists make
hour by hour decisions on when and where
the fleet can fish based on numerous sources
of biological information. One of these sources is
molecular genetic data that are used to determine
which populations of in-bounds sockeye
are most abundant. The data are used
in real time to give a sneak preview of where
sampled fish are headed. This helps managers target
abundant populations and shift effort away from
more limited populations. The process starts with
the creation of a baseline. Geneticists sample spawning
fish from populations representing the nine
distinct stocks of the bay. These fish are
genotyped in the lab for select genetic markers
that can be compared against the incoming sockeye. The Port Moller test
fishery occurs down the Alaska peninsula along a
transect between Port Moller and Cape Newenham where the
sockeye are roughly a week from reaching the fishery. A small appendage called
the axillary process is clipped from the salmon
and sped to Anchorage. Upon arrival at the
lab, the tissue sample undergoes an abstract
transformation from tissue to liquid to letters to
numbers as fast as possible. The samples are first
built into the database where the information
linked to each fish is stored and tracked. The bulk of the sample is
saved for quality control and future use, and the rest
is used for DNA extraction. Before being genotyped, the
DNA must first be isolated. A series of enzymes and
digests remove unwanted tissue so that the purified DNA
is available for analysis. Genotyping is a process
that characterizes the DNA of each
fish for reference genetic markers
providing signals that can be used to compare the
DNA to the baseline data set and determine the genetic
stock of origin for the fish. A liquid handling robot
adds chemicals and DNA to a microfluidic chip where
over 9,000 reactions take place– each one specific to a different
genetic marker and fish. The DNA then undergoes a process
called PCR, polymerase chain reaction, that makes millions of
copies of each genetic marker. The amplified DNA is run
through another machine that scans and scores the
genotypes providing the raw data to compare
against the baseline. The tissue has now been
transformed into letters. The final step of the process
is a statistical analysis that converts the
letters into numbers, estimates of the
relative abundance of fish from each
of the major stock’s currently swimming
towards Bristol Bay. Fishery managers received the
stock composition estimates while the fish are still
several days from arrival to the fishing grounds. And this information is factored
into management decisions. Through this process,
the fleet and economies benefit with increased
catches, while the risk of over-harvesting less
abundant stocks is minimized. More and more
Alaskan fisheries are using these genetic
techniques helping to protect the long-term
sustainability of our resources for the well-being of
the people of Alaska. [MUSIC PLAYING]

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