Walden et al.: Measuring change in productivity of a fishery with the Bennet-Bowley indicator 
277 
Each sector must hold an ACE (which includes both 
landings and discards) for all species in an area where 
a vessel is to fish. Because different species are often 
caught together in a single area, stocks for which where 
there is a low overall quota have the potential to shut 
off fishing of more abundant stocks, and are referred 
to as “choke” stocks. Once an ACE is exhausted for a 
single species in a sector, no further fishing in the stock 
area can take place by sector members, thereby limit- 
ing fishing for other species for which sectors have an 
available ACE. Essentially, there is not enough avail- 
able supply of ACE for these stocks to satisfy demand 
for an ACE within the sector. Depending on the trading 
rules for a given sector, members can go outside their 
own sector to lease additional ACE if it is available 
and needed. 
Before Amendment 16, vessels did not operate under 
hard quotas for most stocks, but rather under target 
TACs, which were set for the fishery as a whole. Under 
a target TAC, fishing could continue even if the TAG 
was exceeded, and then additional fishing restrictions 
would be put in place the following fishing year to ad- 
just the harvest to an appropriate level given the ex- 
cess harvest. In some respects, the catch share system 
is more restrictive than the past controls of fishing ef- 
fort, although sector members can request waivers from 
some of the individual regulations on fishing effort that 
still exist. We also note that the hard quotas imposed 
would still be part of any management system chosen. 
When sectors were proposed as a management option, 
there was a great deal of uncertainty about future quo- 
tas. Nevertheless, it was hoped that the sector system 
would help stabilize a fleet that had been in a state of 
decline for several years. There was a sense that the 
system would allow the fishing fleet to get away from 
the “regulatory treadmill” that had plagued it for years 
with continually changing regulations to control fishing 
effort (Lee and Thunberg, 2013). 
During the first year of the plan, roughly 98% of 
the ACE was held by vessels that joined sectors (Lee 
and Thunberg, 2013). It should be noted that each sec- 
tor acts independently to further the self-interest of 
its members. Generally, vessel owners within a sector 
have been treating the quota they bring into a sector 
as their own allocation, such as they would have done 
within an ITQ system. Each sector member is jointly li- 
able with other sector members if the sector exceeds its 
allocation for any stock. A large amount of monitoring 
takes place within sectors to ensure that allocation for 
any species is not exceeded. 
Vessel owners that elected not to join a sector are al- 
lowed to use their vessels under the “common pool” sys- 
tem, where they are subject to regulations on fishing 
effort, along with an aggregate allowable catch limit 
(ACL) for each species. Under this system, each vessel 
is allocated a number of fishing days for the entire fish- 
ing year, and vessels are allowed to lease, buy, or sell 
days with other members of the common pool. However, 
trading is highly restricted because vessels can trade 
only with other vessels of similar size. This restriction 
was meant to prevent days from being transferred from 
vessels with low fishing power to those with higher fish- 
ing power. Vessels under the common pool system are 
also subject to the same year round area closures as 
are vessels fishing in the catch share system; moreover 
they are subject to seasonal closures from which sector 
vessels may obtain an exemption. The ACL applies to 
all vessels in the common pool and could potentially 
lead to fishing derbies as vessels try to fish their days 
as quickly as possible before the fishery is shut down. 
Currently, the ACLs for the common pool are divided 
into 3 trimesters to smooth catch levels over the year. 
There are several different types of fishing ves- 
sels that harvest species managed in the fishery, but 
we limit this study to vessels which used otter trawl, 
gillnet, or longline gear and landed catch on identified 
groundfish trips. These gear groups are used to harvest 
the majority of the landings in this fishery and are con- 
sistent with the methods used by others to assess pro- 
ductivity change in this fishery (Murphy et al., 2015). 
Otter trawl nets are towed behind a vessel to catch fish 
and are considered a mobile gear. Fixed panels of nets 
are used with gillnet vessels and baited hooks on set 
lines in the water column are used with longline ves- 
sels, and both types of vessels then retrieve the fishing 
gear after a certain amount of time. Both gears are con- 
sidered fixed gear. Between 2007 and 2013, the number 
of vessels in these gear groups declined dramatically, 
from 585 to 283 (Table 1). On average, the size of the 
vessels (by tonnage and horsepower) increased over the 
same time period, whereas the average number of trips 
declined and average days at sea increased. During 
2013, the average number of trips was quite low (28.9), 
whereas the average days spent fishing increased to 
55.2, the highest level during the time period. Average 
revenue, which was based on all species caught on trips 
which were identified as a multispecies trips, peaked 
in 2011 at $298,400 (U.S. $2010, Table 1). After 2011, 
revenue declined for the following 2 years. After imple- 
mentation of the catch share system, revenues earned 
were higher than the 3 years before implementation of 
the management plan (2007-2009). 
Data 
In order to derive the BB indicator, data on quanti- 
ties landed, inputs used to produce the correspond- 
ing landings, prices paid for the landings, and prices 
paid for the inputs used in the production process are 
needed. Because of the large number of species land- 
ed by groundfish vessels, the groundfish speices were 
separated into 6 different groups. Additionally, monk- 
fish ( Lophius americanus ) was included in one of the 
groupings and the barndoor skate ( Dipturus laevis), ro- 
setta skate ( Leucoraja garmani ), winter skate ( Leuco - 
raja ocellata), clearnose skate ( Raja eglanteria), thorny 
skate ( Amblyraja radiata), little skate ( Leucoraja erina- 
cea), and smooth skate ( Malacoraja senta ) were broken 
out into their own category. These species are caught 
as bycatch on groundfish trips. The species groupings 
