276 
Fishery Bulletin 115(3) 
et al., 2015). What is usually important to managers 
and others is how policy changes have impacted pro- 
ductivity separately from changes in biomass, which is 
why a biomass-adjusted measure is desired. 
Because we wish to isolate the change in productiv- 
ity that is associated with changing outputs and inputs 
from a productivity change associated with changing 
fish biomass, a method needs to be used to separate 
productivity change from the change in biomass in the 
overall productivity metric. We follow the approach 
used by Jin et al. (2002) and construct an indicator 
of change in biomass which is then subtracted from 
the overall BB indicator. In this way, we are treat- 
ing biomass as an input, recognizing that biomass is 
then transformed into an output by the fishing vessel. 
However, the biomass measure is subtracted from the 
overall BB indicator, rather than at the individual ves- 
sel level. From a social planner’s perspective, biomass 
that is not harvested by the fleet during the current 
production period, has the potential to be transformed 
into an output in the next period. In our paradigm, 
the biomass is not under control of the vessel, and im- 
provements in biomass in subsequent periods do not di- 
rectly translate into increased future harvests because 
managers set the total allowable catch for each period. 
The biomass indicator we choose has been devel- 
oped previously and is called a “volume indicator” (VI) 
(Moosberg et al. 1 ). The VI is calculated as follows: 
W = |(p t+1 + p')(s t+1 -s') 
1 ( B 'I (6) 
V'' t+i t+i „t+i„t , „t„t+i _t„t 
— s b ~ Pb s b + Pb s b — Pb s b I > 
where s = the spawning stock biomass of species b in pe- 
riod t or f+1; and 
p = the price of species b in period t or t+ 1. 
The VI is needed for multispecies fisheries so that 
all species in the multispecies complex can be included 
in a single composite indicator. However, the same for- 
mula can also be used for a single species fishery. After 
VI has been calculated, it is then subtracted from the 
unadjusted BB indicator to arrive at what we term a 
“biomass adjusted” indicator of productivity: 
= (7) 
where subscript BA = biomass adjusted; 
subscript BU = biomass unadjusted; and 
t = time period. 
The northeast multispecies fishery 
Before describing the data that are used in the BB in- 
dicator, a brief description of the fleet and fishery are 
1 Moosberg, H.J.,R. Fare, S.Grosskopf, and P.Roos, 2007. Vol- 
ume and price indicators: decomposition and revenue with 
an application to Swedish pharmacies, 8 p. Department of 
Economics. Oregon State Univ., Corvallis, Oregon. 
in order. There are 13 fish species included in the fish- 
ery management plan for what is commonly referred 
to as the New England groundfish fishery; additional 
species are caught as bycatch and are not considered 
part of the fishery management plan. The species in- 
cluded in the New England groundfish fishery are the 
American plaice ( Hippoglossoides platessoides ), Atlan- 
tic cod ( Gadus morhua), Atlantic halibut ( Hippoglos - 
sus hippoglossus ), pollock ( Pollachius virens), Atlantic 
wolffish ( Anarhichas lupus), haddock ( Melanogrammus 
aeglefinus), ocean pout ( Zoarces americanus), Acadian 
redfish ( Sebastes fasciatus), white hake ( Urophycis 
tenuis), windowpane ( Scophthalmus aquosus), winter 
flounder ( Pseudopleuronectes americanus), witch floun- 
der ( Glyptocephalus cynoglossus), and yellowtail floun- 
der ( Limanda ferruginea). Atlantic wolffish, ocean pout, 
and windowpane are currently prohibited from being 
landed. The fishing fleet operates between Cape Hat- 
teras, North Carolina, and the U.S.-Canadian border. 
In fishing year 2013 (1 May 2013-30 April 2014), the 
total exvessel value of landings from groundfish species 
landed in the fishery was approximately $55.2 million 
(U.S $2010), although revenue from both groundfish 
and non-groundfish species landed on groundfish trips 
was approximately $270 million. Revenue was estimat- 
ed on the basis of 327 vessels that completed a desig- 
nated groundfish trip. 
In May 2010, Amendment 16 to the northest mul- 
tispecies plan (available at website, accessed March 
31, 2017) was implemented, which expanded the use 
of catch shares within a voluntary sector system. Ves- 
sel owners were allocated a share of the total allow- 
able catch (TAG) for 9 different groundfish species 2 on 
the basis of their historical landings. 3 However, vessel 
owners were only allowed to catch their quota if they 
operated within a harvest cooperative (i.e., approved 
fishing sector). The amount of each species that could 
be potentially harvested by a sector (allowable catch 
entitlement, or ACE) is the sum of individual shares 
that each vessel brings into the sector. Sector manage- 
ment then set the rules for managing their portfolio of 
species for the benefit of sector members. Vessel owners 
wishing to buy, lease, or sell their ACE are subject to 
the trading rules for their respective sector. These rules 
may specify that trades take place within the sector be- 
fore transactions are made with owners in a different 
sector. Thus, the ACE is not as freely tradable as an 
ITQ. Additionally, vessels are still subject to year round 
area closure regulations, which were retained from the 
prior plan, but fishermen may request exemptions from 
seasonal closures and trip limits. 
2 Species included the Atlantic redfish, pollock, white hake, 
witch flounder, American plaice, winter flounder, yellowtail 
flounder, Atlantic cod, and haddock. Additionally, some spe- 
cies had TAG assigned by stock area. The qualifying period 
for determining each owner’s TAG was 1996-2006. 
3 Under the prior Amendment 13, 2 small sectors had been al- 
lowed to form which both harvested Atlantic cod from Georg- 
es Bank. Amendment 16 substantially expanded the number 
of allowed sectors. 
