241
Despite their high value, there are currently no management
plans in place for A. subulata in U.K. waters, whilst squid are
strictly managed to differing degrees in other countries.
There is therefore a need to better understand the biology of
U.K. specimens; ascertaining spatiotemporal differences in
age-at-maturity could help determine whether enforcing
byelaws for squid management could be beneficial for conserving stocks. Samples of A. subulata were collected from
surveys on the RV Cefas Endeavour, as well as from
commercial catches from the English Channel. Specimen
length, weight, maturity stage (using Lipinski’s 5-stage
scale) were recorded, and ageing tools were extracted.
Ageing tools (statoliths, beaks and gladii) were also
extracted, prepared, read and analyzed to determine specimen growth rate and age-at-maturity, as well as determining,
for future work, which tool is the most feasible and reliable
for ageing research. Preliminary results of biological analyses and age readings are discussed, along with implications
for fishery management.
13.2.3 The Influence of Environmental Factors
on Berryteuthis magister (Berry, 1913)
Aggregations Density in the Area of the Northern
Kuril Islands
A. Lishchenko
1*
, K. Kivva
1
1
Russian Federal Research Institute of Fisheries and
Oceanography (VNIRO), 107140, Russia, Moscow,
Verkhnaya Krasnoselskaya 17
*corresponding author: gvajta@ya.ru
Keywords: Berryteuthis magister, Cephalopoda,
Environmental factors, Aggregations density
The schoolmaster gonate squid Berryteuthis magister
(Berry 1913) is the most exploited cephalopod species in
Russian waters. More than 100000 tones is caught by the
trawling fleet in the area adjacent to the Northern Kuril
Islands annually. The main aim of this work is to study the
influence of environmental factors on the density of B.
magister aggregations on the fishing grounds in this area.
The commercial statistics data, provided by large-capacity
fleet, was obtained from the fishery database. This data set
included: date, time, coordinates, tow speed and depth, volume of catch for each trawling, and total daily catch for the
fishery seasons from 2009 to 2016. Additionally we used
the data set provided by scientific observers which contained detailed information on temperature and aggregations density collected during surveys on B. magister
fishery. Presented work is the continuation of the study
begun in 2013 which showed significant relationship
between bottom temperature, presence of the bottom relief
anomalies and squid aggregation density. Our study confirmed periodical short- term changes both in the volume of
catches and the density of small-scale B. magister aggregations. However unlike previous studies we haven’t confirmed correlations between bottom relief and aggregations
density. Between studied characteristics only bottom temperature showed strong and constant correlation with the
density of squid aggregations. According to this finding we
discuss the role of the bottom temperature as the factor
determining the formation of aggregations, or just an indicator of environmental processes significant for Berryteuthis
magister.
13.2.4 Reproductive Strategies of Bobtail Squids
in the Arctic (Cephalopoda: Sepiolida)
Alexey V. Golikov
1*
, Rushan M. Sabirov
1
1
Kazan Federal University, Kremlyovskaya Street 18,
420008 Kazan, Russia
*corresponding author: golikov_ksu@mail.ru
Keywords: Cephalopoda, Sepiolida, Arctic, Reproductive
Biology, Reproductive Strategy
Morphology of the reproductive system and reproductive
strategies are very important while understanding the life
history of the marine organisms. These characters are especially useful in the organisms living in the critical environmental conditions, such as the Arctic. Reproductive biology
and ecology were studied in arctic-boreal bobtail squid
Rossia palpebrosa Owen, 1834 (326 specimens) and higharctic R. moelleri Steenstrup, 1856 (30 specimens) collected
in the Barents Sea and adjacent waters. Females have
unpaired ovary, left oviduct with oviducal gland, paired
nidamental glands and accessory nidamental glands.
Fecundity in mature females is 120–274 (191 ± 8.84)
oocytes in R. palpebrosa and 310–531 (396 ± 48.32) oocytes
in R. moelleri with mature oocyte diameter 6.1–11.4
(8.7 ± 0.9) mm, 15.00–37.73 (21.97 ± 3.18) % of mantle
length and 8.0–13.0 (11.1 ± 1.1) mm, 11.94–19.40
(16.24 ± 1.23) % accordingly. Early stages of oocytes development are absent earlier during ontogenesis in comparison
to tropical and temperate cephalopods. Males have unpaired
testis occupying asymmetric position and spermatophoric
complex with loop-like coiled basal part of the spermatophoric sac. Spermatophore numbers are 13–62 (31 ± 2) with
length 8.9–19.0 (13.5 ± 0.08) mm, 30.00–54.21
(41.50 ± 0.26) % in R. palpebrosa and 84–141 (109 ± 6)
with length 17.5–21.7 (19.7 ± 0.07) mm, 40.00–53.33
(44.56 ± 0.18) % in R. moelleri. Sizes of reproductive products in both species are bigger than in tropical/temperate
Rossiinae, but their number is lower. Rossia thus shows tendency to increase reproductive K-strategy features while
moving northward to the Arctic with secondary increase of
already enlarged oocytes and spermatophores in R. moelleri.
The same time morphology of the reproductive system
clearly bear ancestral features of all Sepiolida. So the morphology of the reproductive system is phylogenetically
explained the same time its functioning being adaptation to
the critical environmental conditions of the Arctic.
Appendices
Despite their high value, there are currently no management
plans in place for A. subulata in U.K. waters, whilst squid are
strictly managed to differing degrees in other countries.
There is therefore a need to better understand the biology of
U.K. specimens; ascertaining spatiotemporal differences in
age-at-maturity could help determine whether enforcing
byelaws for squid management could be beneficial for conserving stocks. Samples of A. subulata were collected from
surveys on the RV Cefas Endeavour, as well as from
commercial catches from the English Channel. Specimen
length, weight, maturity stage (using Lipinski’s 5-stage
scale) were recorded, and ageing tools were extracted.
Ageing tools (statoliths, beaks and gladii) were also
extracted, prepared, read and analyzed to determine specimen growth rate and age-at-maturity, as well as determining,
for future work, which tool is the most feasible and reliable
for ageing research. Preliminary results of biological analyses and age readings are discussed, along with implications
for fishery management.
13.2.3 The Influence of Environmental Factors
on Berryteuthis magister (Berry, 1913)
Aggregations Density in the Area of the Northern
Kuril Islands
A. Lishchenko
1*
, K. Kivva
1
1
Russian Federal Research Institute of Fisheries and
Oceanography (VNIRO), 107140, Russia, Moscow,
Verkhnaya Krasnoselskaya 17
*corresponding author: gvajta@ya.ru
Keywords: Berryteuthis magister, Cephalopoda,
Environmental factors, Aggregations density
The schoolmaster gonate squid Berryteuthis magister
(Berry 1913) is the most exploited cephalopod species in
Russian waters. More than 100000 tones is caught by the
trawling fleet in the area adjacent to the Northern Kuril
Islands annually. The main aim of this work is to study the
influence of environmental factors on the density of B.
magister aggregations on the fishing grounds in this area.
The commercial statistics data, provided by large-capacity
fleet, was obtained from the fishery database. This data set
included: date, time, coordinates, tow speed and depth, volume of catch for each trawling, and total daily catch for the
fishery seasons from 2009 to 2016. Additionally we used
the data set provided by scientific observers which contained detailed information on temperature and aggregations density collected during surveys on B. magister
fishery. Presented work is the continuation of the study
begun in 2013 which showed significant relationship
between bottom temperature, presence of the bottom relief
anomalies and squid aggregation density. Our study confirmed periodical short- term changes both in the volume of
catches and the density of small-scale B. magister aggregations. However unlike previous studies we haven’t confirmed correlations between bottom relief and aggregations
density. Between studied characteristics only bottom temperature showed strong and constant correlation with the
density of squid aggregations. According to this finding we
discuss the role of the bottom temperature as the factor
determining the formation of aggregations, or just an indicator of environmental processes significant for Berryteuthis
magister.
13.2.4 Reproductive Strategies of Bobtail Squids
in the Arctic (Cephalopoda: Sepiolida)
Alexey V. Golikov
1*
, Rushan M. Sabirov
1
1
Kazan Federal University, Kremlyovskaya Street 18,
420008 Kazan, Russia
*corresponding author: golikov_ksu@mail.ru
Keywords: Cephalopoda, Sepiolida, Arctic, Reproductive
Biology, Reproductive Strategy
Morphology of the reproductive system and reproductive
strategies are very important while understanding the life
history of the marine organisms. These characters are especially useful in the organisms living in the critical environmental conditions, such as the Arctic. Reproductive biology
and ecology were studied in arctic-boreal bobtail squid
Rossia palpebrosa Owen, 1834 (326 specimens) and higharctic R. moelleri Steenstrup, 1856 (30 specimens) collected
in the Barents Sea and adjacent waters. Females have
unpaired ovary, left oviduct with oviducal gland, paired
nidamental glands and accessory nidamental glands.
Fecundity in mature females is 120–274 (191 ± 8.84)
oocytes in R. palpebrosa and 310–531 (396 ± 48.32) oocytes
in R. moelleri with mature oocyte diameter 6.1–11.4
(8.7 ± 0.9) mm, 15.00–37.73 (21.97 ± 3.18) % of mantle
length and 8.0–13.0 (11.1 ± 1.1) mm, 11.94–19.40
(16.24 ± 1.23) % accordingly. Early stages of oocytes development are absent earlier during ontogenesis in comparison
to tropical and temperate cephalopods. Males have unpaired
testis occupying asymmetric position and spermatophoric
complex with loop-like coiled basal part of the spermatophoric sac. Spermatophore numbers are 13–62 (31 ± 2) with
length 8.9–19.0 (13.5 ± 0.08) mm, 30.00–54.21
(41.50 ± 0.26) % in R. palpebrosa and 84–141 (109 ± 6)
with length 17.5–21.7 (19.7 ± 0.07) mm, 40.00–53.33
(44.56 ± 0.18) % in R. moelleri. Sizes of reproductive products in both species are bigger than in tropical/temperate
Rossiinae, but their number is lower. Rossia thus shows tendency to increase reproductive K-strategy features while
moving northward to the Arctic with secondary increase of
already enlarged oocytes and spermatophores in R. moelleri.
The same time morphology of the reproductive system
clearly bear ancestral features of all Sepiolida. So the morphology of the reproductive system is phylogenetically
explained the same time its functioning being adaptation to
the critical environmental conditions of the Arctic.
Appendices