Protected Species and Marine Aquaculture Interactions

(A)
(B)
Figure 2. Representative
schematics of submerged
offshore longline
systems used for suspension
culture of mussels.
View (A) shows individual
grow out socks
suspended from the
backbone (Lindell 2014).
View (B) shows a single
looped grow rope configuration
(adapted from
Vincent Prien, Isles of
Shoals Mariculture, LLC,
Rye, NH, pers. comm.).
be deployed in the open ocean and in high energy nearshore environments (Langan
et al. 2010). Figure 2 shows typical specifications for single longlines. Other illustrations
of longline gear may be found at the Catalina Sea Ranch website (Catalina Sea
Ranch 2015).
At a typical commercial farm, multiple backbone lines are arrayed in parallel rows
submerged several meters (5– 20m) below the surface using a system of anchors and
buoys. The longlines may be 150– 300m in length. Submerged floats keep the vertical
lines running up from the anchors (Figure 2) and the horizontal longlines properly
oriented in the water column and prevent the lines from becoming entangled with
each other. Arrays of these longlines are deployed at a farm site spaced 10– 20m apart.
In many parts of the world, a single farm may include several hundred longlines covering
hundreds of acres. Currently in the United States, farms are typically being permitted
at smaller scales (less than 100 acres), though it is anticipated that scaling up
will follow once the domestic industry expands in the near future.
Each longline is suspended in the water column by two submerged corner floats.
These corner floats, in combination with the anchors and the overall geometry of the
Protected Species & Mussel longline aquaculture interactions | 9