280 
Fishery Bulletin 115(3) 
Table 3 
Bennet-Bowley productivity indicator values unadjusted for biomass change for continuing, entering, and 
exiting vessels for the period 2007-2013 in the northeast groundfish fishery. Note: 2010 was the year in 
which the catch share system was implemented for this fishery. 
Entering vessels Continuing vessels Exiting vessels 
No. of No. of No. of Total value 
Year 
Indicator 
vessels 
Indicator 
vessels 
Indicator 
vessels 
of BB indicator 
2008 
0.06 
51 
0.39 
484 
-0.08 
101 
0.37 
2009 
0.03 
49 
0.21 
440 
-0.07 
95 
0.17 
2010 
0.04 
36 
-0.47 
335 
-0.36 
154 
-0.79 
2011 
0.10 
52 
0.04 
292 
-0.13 
79 
0.01 
2012 
0.07 
52 
-0.75 
286 
-0.08 
58 
-0.75 
2013 
0.02 
27 
-0.10 
256 
-0.09 
82 
-0.18 
more to the indicator than vessels continuing within 
the fishery when both values were positive. However, 
the number of vessels in the group continuing within 
the fishery each year was far greater than the number 
of entering vessels, and the additive nature of the indi- 
cator means that they should be contributing more to 
the indicator unless entering vessels were much more 
productive than continuing vessels. Even if entering 
vessels are more productive, their low numbers mean 
that, in aggregate, they do not contribute as much to 
the metric of fleet productivity. The large contribution 
by continuing vessels in the aggregate measure is con- 
sistent with that of other studies, which show that con- 
tinuing vessels were the largest group after a change to 
a catch share system and contributed the most to ag- 
gregate productivity change (Walden et al., 2012; Fare 
et al., 2015). A catch share system, whether it is a co- 
operative system or an ITQ system, creates a barrier to 
entry owing to limited quotas and the initial rules for 
allocation. Entering vessels may need to buy or lease 
a quota, and therefore be more productive to offset the 
quota cost. 
There was a core group of vessels within the fleet 
in our study that was present in all 6 years. In order 
to determine whether the move to a catch share sys- 
tem changed the productivity of these vessels, a non- 
parametric Kruskal-Wallis test was used to compare 
their normalized BB indicators before and after catch 
shares were implemented on an individual vessel ba- 
sis. Results from the Kruskal-Wallis test indicated 
that the distributions were not equal (chi-square: 94.9, 
df=l), and examination of the BB indicator showed 
that the postcatch share, the median value of the BB 
indicator (-0.003), was lower than the precatch share 
(0.002). This result was consistent with the results for 
the whole fleet, which showed productivity declines af- 
ter the catch shares were implemented. It is also con- 
sistent with separate findings for this fishery, which 
showed declines in productivity after the catch share 
system was put in place (Murphy et al., 2015). 
A final question regarding these core vessels — a 
question that existed throughout the entire study pe- 
riod — was whether there were persistent differences 
in performance between the vessels within this group. 
In order to examine this question, vessels were sepa- 
rated into quartiles depending on unadjusted produc- 
tivity (i.e., without biomass considered) in 2008. Un- 
adjusted productivity was used because the VI used 
to measure a change in biomass affected all vessels 
equally. In other words, it did not shift a vessel into 
a different quartile. Productivity for each group was 
then tracked for the remaining years in the study 
(Fig. 1). Tracking of vessel groups allowed us to see 
whether the vessesl with higher productivity contrib- 
uted the most to the indicator throughout the remain- 
ing years. 
Vessels that were in the top quartile (i.e., with a 
higher degree of productivity) during 2008 contributed 
positively to the overall productivity gain in both 2008 
and 2009, and, as a group, contributed more than the 
other 3 quartiles combined. In 2010, this same group of 
vessels contributed the most to productivity decline. In- 
terestingly, the bottom quartile group in 2008 was the 
only group that showed a positive productivity gain in 
2010. In 2011, the top 2008 quartile contributed nega- 
tively to overall productivity gain, whereas the other 3 
quartiles contributed positively. In 2012 the top 2008 
quartile group contributed the most to productivity de- 
cline, although there was little difference among all 4 
groups. In 2013, all 4 groups had a negative produc- 
tivity gain, and the third quartile group contributed 
the most to productivity decline. Summarizing these 
findings in terms of the top 2008 vessels shows that 
productivity gains for these vessels before catch shares 
turned into productivity declines after the switch to the 
catch share system. 
The reversal in economic status for the top quar- 
tile indicates that, before the implementation of catch 
shares, those vessels were successful within the frame- 
work of regulations controlling fishing effort that ex- 
isted during that time period and perhaps aided by 
permission to lease fishing days and the lack of hard 
