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Please quote as: Lancaster, J. (Ed.), McCallum, S., Lowe A.C., Taylor, E., Chapman A. & Pomfret, J. (2014).
Development of detailed ecological guidance to support the application of the Scottish MPA selection guidelines in
Scotland’s seas. Scottish Natural Heritage Commissioned Report No.491. Orange Roughy – supplementary
document.
Orange Roughy
Scientific name: Hoplostethus atlanticus
Territorial/Offshore waters: Offshore
Orange roughy (Hoplostethus atlanticus) is a benthopelagic species, inhabiting
continental slopes and seamounts at depths below 600m but mostly between 900
and 1700m (Bailey et al. 2009). This fish, which commonly reaches 60 cm in length,
is bright brick red in colour when caught, however this colour fades to a yellowish
orange after death (hence its name). It has a deep and compressed body and a large
head with an oblique mouth and large eyes. This species has been commercially
exploited in the past but Total Allowable Catch has now been reduced to zero across
the North-east Atlantic.
Functional Links and Connectivity
Functional links and associations with Priority Marine Features

Seamounts and seamount communities: Populations of orange roughy are
often concentrated around topographical features such as seamounts where
they are known to aggregate to feed and spawn (OSPAR, 2010)

Continental slope: Outside of spawning aggregations, orange roughy are
widely distributed at low densities across the Hebridean continental slope
where juveniles have been caught in fishing surveys.
Functional links with wider Scottish marine ecosystem
The ecology of this species in the North Atlantic is poorly understood but studies of
the Rockall Trough by Mauchline & Gordon (1984) between 1973 and 1981 showed
that orange roughy exploit the benthopelagic fauna for prey, especially mysids and
decapod crustaceans. Using this and additional data, Howell et al. (2009) showed
that the total diet for orange roughy likely consists of: prawns and shrimp (~40%)
mesopelagic fish (~33.4%), benthopelagic fish, other benthic invertebrates
cephalopods as well as a small amount of zooplankton. There is no information to
suggest that orange roughy play a specific role as a keystone species or habitat
modifier, although its position as an opportunistic predator is likely to influence the
structure of mesopelagic and benthopelagic community composition.
Connectivity
Orange roughy has a widespread distribution on the continental slope, banks and
seamounts to the west of Scotland. They aggregate to spawn around seamounts
(OSPAR 2010). The main site of spawning aggregations in Scottish waters is
believed to be the Hebrides Terrace Seamount which was the location of a target
fishery for the species in the early 1990s (ICES, 2011). Catches from this area
declined to low levels in 1993 following depletion of the stock. There is also some
evidence for aggregation sites on Rosemary Bank and Anton Dohrn (eg. Bridger
1978). MSS surveys have recorded juvenile orange roughy on the Scottish
continental slope, mainly south of 58oN.
White et al. (2009) found North East Atlantic populations of orange roughy to be
typically K-selected1, exhibiting panmixia, or random mating. The data suggests that
adult orange roughy are migrating large distances (~200miles) and mating with
different populations. The long distance migration is considered to be the most likely
reason for the genetic mixing on such a wide geographical scale, the alternative
being sufficient dispersal of eggs/larvae, which is discounted by Zeldis et al. (1995
cited in White et al., 2009) who suggest that eggs could travel no more than 50km,
with observed displacement being 18km from the spawning area.
Coherence
Population structure
Orange roughy has a widespread distribution on the continental slope, banks and
seamounts to the west of Scotland. They aggregate to spawn around seamounts
between January and April. Known spawning aggregation sites in Scottish waters
include the Hebrides Terrace Seamount and possibly Anton Dohrn and Rosemary
Bank Seamounts but this has not been confirmed.
Orange roughy is a very slow-growing species with a longevity of around 130 years
(Allain & Lorance, 2000). They do not reach sexual maturity until around 28 years
and have relatively low fecundity (Minto & Nolan 2006). It also is likely that all orange
roughy do not spawn every year (Annala et al., 2003). All this leads to the conclusion
of very low productivity and high vulnerability to depletion by fisheries exploitation.
Ecological variation across Scottish waters
There is insufficient evidence to determine whether individual spawning aggregations
constitute discrete populations. Genetic evidence suggests that there is no
population structure across the North Atlantic (White et al. 2009). However, studies
on populations in the southern hemisphere have produced equivocal results; genetic
studies have generally failed to discriminate between stocks while those that have
focused on variation in the environmental characteristics experienced by the fish
during its life (e.g. otolith microchemistry, otolith structure, morphometric differences
and parasite analysis) have generally shown that adult orange roughy are relatively
sedentary and that stocks are fairly isolated from one another (ICES 2002).
1
In the K-selected strategy, populations tend to remain near the carrying capacity (K), the maximum
number of individuals that the environment can sustain. Individuals in a K-selected population.
2
Viability
It is uncertain whether separate spawning locations of orange roughy constitute
discrete populations. It has been suggested that individual orange roughy may chose
to spawn in any suitable location rather than displaying fidelity to a particular
aggregation site (White et al., 2009). Orange roughy are most vulnerable to
exploitation when aggregating to spawn and so protected areas should be focused
on aggregation sites. In the absence of precise information on small scale location of
aggregations within the seamount features, adequate protection could be achieved
by protecting all waters of suitable depth (600-1700m) on the seamount. Protected
areas are unlikely to be a suitable management measure for orange roughy outside
spawning aggregation sites due to their widely dispersed distribution.
Indicators of Least Damaged/More Natural
The sensitivity of orange roughy to pressures associated with human activities is
included in the Features, Activities, Sensitivities Tool (FeAST; Marine Scotland,
2013). Information on indicators of orange roughy being least damaged or more
natural in Scottish waters has been taken from the OSPAR Case Reports for
Threatened and/or Declining Species and Habitats (OSPAR, 2010) (Table 1).
Table 1. Indicators of damage and naturalness
Indicator of Naturalness
Indicator of Damage
Maintenance of catch per unit Reductions in CPUE indicating a
effort (CPUE) over time.
decrease in population size
(OSPAR, 2010)
Maintenance of catch
distribution over time
size
Reductions
in
the
size
distribution of individuals caught
indicating the removal of the
higher age classes within the
population (OSPAR, 2010)
Potential Sources of Damage
Extraction (fishing;
OSPAR
2010)
Extraction (OSPAR 2010)
Risk Assessment
The details of the assessment of risk for each MPA search feature is addressed in a
separate report (Chaniotis et al., 2014).
Recovery Potential
Extraction
The slow growth rate and longevity of orange roughy means that recovery of
depleted populations is likely to be very slow.
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Geographical Variation
Orange roughy has a range that extends across the Far West MPA region, with
records along the continental slope and on the Rosemary Bank, Anton Dohrn and
Hebrides Terrace seamounts. Commercial landings are also reported at very low
levels from the southern part of the North Scottish MPA region (ICES 2011) but there
are no spawning aggregations in this area and it can probably be considered as an
extension of the range in the Far West region.
Geographical context
H. atlanticus is recorded from deep water habitats in the Atlantic, Pacific and Indian
oceans. The fishery in New Zealand is the world’s largest (OSPAR, 2008).
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References
Allain, V. & Lorance P. 2000. Age estimation and growth of some deep-sea fish from
the Northeast Atlantic ocean. Cybium 24(3 suppl.), 7-16
Annala, J.H., Sullivan, K.J. O’Brien C.J., Smith N.W. McL & Grayling S.M. (comp.)
2003. Report from the fishery assessment plenary, May 2003: stock assessments
and yield estimates. 616pp. Ministry of Fisheries. (Unpublished report held in NIWA
Library, Wellington).
Bailey, D. M., Collins, M. A., Gordon, J. D. M., Zuur, A. F. & Priede, I. G. 2009. Longterm changes in deep-water fish populations in the northeast Atlantic: a deeper
reaching effect of fisheries? Proceedings of the Royal Society Of Biological Sciences,
276(1664), 1965-1969.
Bridger J. P. 1978. New deep-water trawling grounds to the west of Britain. Ministry
of agriculture Fisheries and Food directorate of fisheries research laboratory leaflet
No. 41. Lowestoft.
Chaniotis, P.D., Cunningham, S., Gillham, K. & Epstein, G. 2014. Assessing risk to
Scottish MPA search features at the MPA regional scale. Final report produced by
the Joint Nature Conservation Committee, Scottish Natural Heritage and Marine
Scotland for the Scottish Marine Protected Areas Project.
Howell, K.L., Heymans, J.J., Gordon, J.D.M., Duncan, J., Ayers, M., Jones, E.G.
2009. DEEPFISH Project: Applying an ecosystem approach to the sustainable
management of deep-water fisheries. Part 1: Development of the Ecopath with
Ecosim model. Scottish Association for Marine Science, Oban. U.K. Report no. 259a.
ICES. 2002. Report of the Working Group on the Biology and Assessment of DeepSea Fisheries. April 2002 ICES CM 2002/ACFM:16
ICES 2011. Report of the Working Group on the Biology and Assessment of Deepsea Fisheries Resources (WGDEEP) ICES CM 2011/ACOM:17
Mauchline, J. & Gordon, J.D.M. 1984. Occurrence and feeding of berycomorphid and
percomorphid teleost fish in the Rockall Trough. Journal Conseil International pour
l'Exploration de la Mer, 41, 239-247.
Marine Scotland. 2013. Features, Activities, Sensitivities Tool (FeAST) online
resource. Available from:
http://www.scotland.gov.uk/Topics/marine/marine-environment/FEAST-Intro
Minto, C. & Nolan, C.P. 2006. Fecundity and maturity of orange roughy
(Hoplostethus atlanticus Collett 1889) on the Porcupine Bank, Northeast Atlantic.
Environmental Biology of Fishes, 77, 39-50.
OSPAR 2010. Background Document for the Orange roughy Hoplostethus atlanticus
OSPAR
Commission
2010.
http://qsr2010.ospar.org/media/assessments/Species/P00483_orange_roughy.pdf
Downloaded 01/12/2011
White, T.A., Stefanni, S., Stamford, J., & Hoelzel, A. 2009. Unexpected panmixia in a
long-lived, deep-sea fish with well-defined spawning habitat and relatively low
fecundity. Molecular Ecology, 18(12), 2563-2573
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