Estimating age and growth rate in Architeuthis dux

Dr. Steve O'Shea's paper is a guide for marine biologists studying giant squid

By Dr. Steve O'Shea

Auckland University of Technology, Earth and Oceanic Sciences Research Institute, Private Bag 92 006, Auckland, New Zealand.


Note: Steve welcomes discussion in TONMO's Architeuthidae forum.

Architeuthis is a leviathan amongst cephalopods, with mantle lengths reputed to, but in reality unlikely to ever approach 4−6 metres (Clarke 1966, Roper & Boss 1982). We stress the unlikely nature of such exaggerated mantle lengths because a marked contrast exists between ‘4−6 metres’ and measurements based on numerous stranded specimens, sperm whale gut contents, and fisheries bycatch, where mantle length characteristically ranges ~ 0.5−2.4 m (Aldrich 1991, Roeleveld & Lipiński 1991, Jackson et al. 1991, Gauldie et al. 1994, Fernandéz-Nunez & Hernandez-Gonzàléz 1995, Norman & Lu 1997, Lordan et al. 1998, Förch 1998, and personal observation).


As nobody has been able to rear deep-sea species of squid in captivity (yet), especially Architeuthis, we really have no idea how old this species is, and how fast it grows. Published estimates for growth rate in Architeuthis vary from 5.06−2.62 mm mantle length (ML)/day (d-1), with larger individuals appearing to grow faster than smaller individuals (Tables 1−3). These estimates are based on examination of two tiny bones (statoliths; Figs 1, 2) removed from the ventral surface of the squid’s head, that in cross-section reveal numerous rings, much like those in sectioned tree trunks; by counting the rings and comparing this to the mantle length of the squid we come up with an estimate of both growth rate and age. The problem is that these estimates have not been validated for deep-sea species — we really don’t know if an individual ring on the statolith is deposited on a daily basis. Although daily growth increments within the cephalopod statolith have been validated for Todarodes (Nakamura & Sakurai 1991), Illex illecebrosus (Dawe et al. 1985, Hurley et al. 1985), Sepioteuthis lessoniana (Jackson 1990), Idiosepius pygmaeus (Jackson 1989), and Alloteuthis subulata (Lipinski 1986), they have not for Architeuthis, nor for any other deep-sea/cold water species of cephalopod (although the growth rings are similar in appearance to daily growth rings of other squids (Dunning & Lu 1998)).


A wide variety of growth curves have been reported for squids, e.g., Boyle (1990) for Loligo sp., wherein it is argued that cephalopod growth is either slowed drastically or becomes erratic at the onset of sexual maturity. For species with a short-term breeding season, this point of slow growth might be reached simultaneously at the same age and at the same body size by the bulk of the population. In other species, sexual maturity occurs over a very wide range of body sizes. Growth also appears to vary widely from season to season (e.g., Hatfield (1991) for Loligo gahi), and from individual to individual of the same brood when ample food is available (Hurley 1976) and Yang et al. 1986, for Loligo opalescens).


Young squid are capable of fast, exponential growth when food is not limiting (Yang et al. 1986). Asymptotic mantle size as a function of time has been observed in wild populations, e.g., Natsukari et al. (1988) for Photololigo edulis, Spratt (1978) for Loligo opalescens, Patterson (1988) for Loligo gahi (although no evidence for asymptotic growth was found for L. gahi by Hatfield (1991), and for Illex argentinus (Hatanaka et al. (1985)). Linear, logarithmic, or exponential growth has been reported by Hurley (1976), Turk et al. (1986), Yang et al. (1986) and Hatfield (1991) for Loligo opalescens, for L. vulgaris, and L. opalescens respectively — all hatchery-reared animals where presumably neither food limitation nor temperature fluctuation were major issues.


Table 1. Estimated growth rates in Architeuthis (from literature).

Estimated growth rateArchiteuthis mantle lengthSource
5.06 mm ML d-11625 mmBrunetti 1998
4.09 mm ML d-12168 mm Gauldie et al. 1994
~ 3.57−2.62 mm ML d-13 approximately 1000 mmLordan et al. 1998
~2.76 mm ML d-1422 mmJackson et al. 1991

New Zealand Architeuthis statoliths, when viewed from posterior and anterior views (Figs. 1, 2), are similar to those of Roeleveld & Lipiński (1991), Gauldie et al. (1994) and Lipinski (1997). They have a strong wing with regularly indented dorsal and lateral lobes, cavernous anterior “proto-sulcal” groove with an in-folding lobe edge, and a prominent rostrum.

While Lordan et al. (1998) present an image of a ground statolith, showing rings near the nucleus, neither they nor others have precisely defined its’ position in the statolith. Analysis of the dorso-lateral lobes under SEM indicated that they emanated from the capella region; intuitively, the nucleus should be contained therein. Thus, in this study, transverse thin sections of the Architeuthis statolith were orientated orthogonal to each other through the capella, dorso-ventrally or medial-laterally using the left and right statoliths of one specimen (see Fig. 2). Resultant thin sections demonstrated clearly that the nucleus did lie within the capella region, close to its anterior edge (Figs 3, 9).


The statoliths are complex, having almost transparent areas of crystallisation posteriorly and anteriorly but strong mid-line proteinaceous zones in the dorso-nuclear axis (Fig. 3). Marginal zones within the statolith are more transparent than near the nucleus, indicating less protein deposition, possibly indicative of slower growth zones. The statolith of Gonatus fabricii is similarly partitioned (Kristensen 1980).

At higher magnifications (Fig. 4), axial complexities or interruptions are evident. These could be attributable to incorrect alignment of the section, where the grinding plane has effectively crossed over one of the dorso-lateral lobes leading into the capella; the ability to count increments is consequently reduced. Broad mid-axis increments are a common feature at this magnification, with widths of ~ 25 µm comparing well to an average value of ~ 26 µm for similar broad bands, described as ‘dark check-rings’ caused by the fusion of micro-increments, by Gauldie et al. (1994). What periodicity, if any, these broad check rings have is open to speculation, but they do form a regularly repeating construct.

Table 2. Statolith mean increment-width data culled from the literature, or calculated from figures.


Alloteuthis subulata

2.1 µm

Kristensen (1980)

“ “

3, 2.2 to 0.75 µm

Lipinski (1986)

“ “

2.08 µm

Arkhipkin & Nekludova (1993)

Ancistrocheirus lesueurii

10−6 µm, 1.8−2 µm to 0.95 µm

Arkhipkin (1997)

Architeuthis dux

2.46 µm (edge)

Jackson et al. (1991)

“ “

2.5 (nuclear) to 1 µm (edge)

Gauldie et al. (1994)

Enoploteuthis leptura

7 to 2 µm

Arkhipkin (1994)

Idiosepius pygmaeus

0.93 µm

Jackson (1989)

Illex illecebrosus

2.8−1.7 µm

Hurley et al. (1985)

“ “

2.9 µm

Morris & Aldrich (1985)

“ “

2−1.28 µm

Radtke (1983)

Loligo chinensis

1.9 µm

Jackson (1990)

Loliolus noctiluca

1.2 µm (edge)

Jackson (1990)

Moroteuthis robusta

2−1 µm

Bizikov & Arkhipkin (1997)

Nototodarus sloanii

2.9 µm (@ 250 µm statolith) to 2.3 µm (@ 700 µm statolith)

Uozumi & O’Hara (1993)

Ommastrephes bartramii

6 to 3.6 µm

Yatsu & Mori (2000)

Pterygioteuthis gemmata

5 to 2.5 µm

Arkhipkin (1997)

Sepioteuthis lessoniana

3.95 µm (edge)

Jackson (1990)

Todarodes pacificus

3.05 µm

Nakamura & Sakurai (1991)

Todarodes saggittatus

2.13 µm

Rosenberg et al. (1981)


giant squid age

giant squid age

giant squid age

giant squid age

Micro-increment pattern and width within the statolith is site specific and depends on the plane of optical focus. Mid-axis increments in the dorso-ventral orientation can be counted as large rings of width ~ 2.22 µm. Defocusing across the axis shows these larger rings to be composed of finer increments with widths of ~ 0.89 µm (Fig. 5). We propose that the larger rings are an artefact of the sub-surface crystallography, caused by an optical summation as light enters and exits the thickness of the preparation. The finer increments may then represent a surface-focused effect, minimising presumed interference or diffraction patterns in the sub-surface layers. This raises the possibility that ring counts within the published literature may be underestimating age since reported counts typically involve rings of width ~ 3 µm in Architeuthis. That lateral axes are smaller than the dorso-ventral ones infers that any available rings will be forced into a tighter agglomeration. Lateral thin-section data shows similar widths of the order of 1−1.5 µm, but also bunches of increments are discernible having broad dimensions of ~ 10 µm (Fig. 6).

Difficulties experienced in interpreting ring appearance are not limited to studies on Architeuthis. Jackson (1994) summed maximum age in several cephalopod species, showing marked variation between studies, raising the possibility that “increment sequences within the statoliths of some species may be ambiguous”. The appearance of 2nd- or 3rd-level banding patterns has been identified by some investigators (Kristensen 1980, Arkhipkin 1997), and the possibility raised that these rings are formed according to lunar cycles.

The regularity of increment appearance can be striking as is seen in a post-nuclear image, antero-laterally aligned with ring widths between 1.25−1.5 µm (Fig. 7). These rings resemble those described for several teleosts (Pannella 1971, Brothers et al. 1976, Jones 1986, Campana & Neilson 1985, Campana 1992).


giant squid age

giant squid age

giant squid age

giant squid age

Postero-medial ring patterns are more complex in dorso-ventral section, with post-nuclear rings reducing in width to ~ 1.2 µm before disappearing to be become broad bands (~ 9 µm) composed of finer (~ 1.85 µm) rings (Fig. 8). By contrast, the orthogonal transverse section in the medial-lateral plane is approximately three times shorter than the corresponding dorso-ventrally aligned section (see Fig. 2). Temporal (age) information across this shorter axis should be condensed in space and time, with very narrow increments exceedingly closely spaced, but with major check marks easier to define. In section, through this axis from an 1125 mm ML specimen, 15−17 sharply defined large rings are apparent (Fig. 9). If these rings were of a lunar/monthly periodicity then this specimen would have an estimated age of ~ 476 days, which falls within the calculated age range of 431 and 1437 days from Table 3.


Defocusing through the preparation reveals finer micro-increments that become unreadable toward the margin (Fig. 10). Upon magnification, the finest rings yet discovered in Architeuthis statoliths are visible just post the presumptive larval hatching check; here their widths are ~ 0.87 µm (Fig. 11), and they are similar to those described previously for the mid-dorsal position. Indeed, average increment widths derived by dividing mid-capella (i.e., nuclear) to dorsal edge distances by the number of counted rings shows a remarkable uniformity with an average of ~ 2.9 µm, compared with those in the published literature (see Table 3). Thus interpretation of total ring number is extremely difficult, especially when placed within the context of validated cephalopod ring widths. For example Nakamura & Sakurai (1991) report ring widths of ~ 3.05 µm from a near adult Todarodes pacificus, and Hurley et al. (1985) report validated width range of 2.8 to 1.7 µm for Illex illecebrosus statoliths.


To add to the difficulties, it is known from the examination of microincrements within teleost otoliths that feeding can affect increment width (Victor 1982) and that differences in growth rate can alter the total number of countable rings (Volk et al. 1995). Raya et al. (1992) report non-daily increments from the statoliths of the sepiod Sepia hieredda. The statolith of Architeuthis is small in comparison to overall mantle length (Lipinski 1997), adding to the complexity and importance of looking for very small rings to substantiate age estimates. We consider that current statolith-based age estimates are to be treated with suspicion as none to date describe consistently fine accretions of increments of the order of 0.87 µm that we have described.


By using the average observed increment widths calculated from the literature for Architeuthis, we derive a value of ~ 2.9 µm (see Table 3, excluding some anomalous counts from alternate axes by Jackson et al. (1991) and Lipinski (1991)). This is close to the mean increment width data observed in a broad range of cephalopod statoliths listed in Table 2. We also propose a lower bound to the mean increment width to be = 0.87 µm. Thus, upper and lower bounds to age, derived using a method similar to Ralston (1985), can be obtained by dividing the statolith nucleus-to-dorsal growth edge distance by both values, giving age estimates differing ultimately by a factor ~ 3 (2.9/0.87). Using this method maximum age is estimated to be 1747 days (~ 4.8 years) in a 1680 mm ML, which is within the maximum likely age speculated to be ~ 5 by Forsythe & van Heukelem (1987). The same specimen has a lower age bound (SFD/2.9 µm) of ~ 1.5 years.


By converting putative age ranges into mean-mantle growth rates, and summing across all specimen lengths, we can suggest two possibilities. First, Architeuthis dux is a fast-growing squid, with a growth rate upper bound of ~ 3.6 mm ML d-1. Second, A. dux is a slow-growing squid, with a growth rate lower bound of ~ 0.97 mm ML d-1. There is, however, no current agreement regarding which model best describes squid growth. Early growth of larvae is exponential (Forsythe & van Heukelem 1987, Bigelow & Landgraf 1993, Bower 1996), while post larval growth is thought to be logarithmic. Therefore, Architeuthis growth rate is likely to fall somewhere between the upper and lower bounds calculated above, and differ at different stages of its life cycle.

Gladius

The periostracum layer of the conus and rostral regions of an Architeuthis gladius are not as well developed as they are in species of the families Ommastrephidae and Gonatidae. In cross section, ommastrephid and gonatid squids manifest strong depositional layering of chitinous-like material (Toll 1990, Bizikov 1991). In contrast to the appearance of the angled ribbing illustrated for Sthenoteuthis oualaniensis by Bizikov, anterior portions of the Architeuthis gladius have prominent chitinous ribs orientated at a more acute angle, almost parallel to the rachis. It appears that the parallel ribs have medial and lateral agreement; one specimen having 6 distinguishable ribs aside the central rachis (Fig. 12).


giant squid age

giant squid age

giant squid age

giant squid age

Eye lens

A whole Architeuthis eye lens thin section is shown in Fig. 13, with the bipartite nature of this lens, characteristic of cephalopods, most apparent. Magnification of the leading lateral edge of the lens showed a consistent series of highly uniform increments (Fig. 14). It is known that these increments exist from early developmental stages (Arnold 1967). The average increment width for these fine lateral rings, as calculated from Fig.14, is ~ 4.06 µm. Presuming these rings are deposited on a daily basis, a putative age can be derived by dividing the nucleus to lateral edge distance of the lens (~ 9 mm) by 4.06 µm — ~ 2217 days (~ 6.1 years). This concurs with the putative age of Architeuthis determined from this specimens’ gladius, ~ 6 years of age. Converting this age to a mean mantle-growth rate gives a value of 1845 mm ML / 2217 days = 0.83 mm d-1, which is close to the lower bound of mean mantle-growth rates estimated from statoliths in Table 3 of ~ 0.97 mm d-1.


giant squid age

giant squid age

It proves difficult to reconcile known adult sizes and weights with historic (1880’s) records of 20 m long squids weighing one tonne — such animals would have to exceed an unprecedented 3 m ML. The estimate of 6 metres maximum mantle length proposed for this animal (Roper & Boss 1982), and the lesser maximum of 4 metres (Clarke 1966) should not be perpetuated — they are both likely to be overestimates of the true maximum mantle length this squid achieves. Of approximately 110 recently examined (over 8 years) specimens the largest we have seen was a fully mature female of ML 2.3 m. Remains of specimens collected in the 1880’s held at the Museum of New Zealand indicate such reported lengths are quite exaggerated, with remains consistent in size with the largest individuals now known, recently collected and examined during this study from local waters.

Table 3. Estimates of growth rate in Architeuthis based on 22 specimens based on statolith microsculpture, and the assumption that micro-increments are deposited daily (as validated in different species of laboratory-reared squids).

source

ML

sex

STL

SFD

sfd/stla

Ring count

SFD/

rings

x=2.9µmk

mm/day

x=0.87µmk

mm/day

herein

1125

2.3

1.25

0.54

*

*

431

2.6

1437

0.8

herein

1845

1.99

1.10

0.55

*

*

379

4.9

1264

1.5

herein

1000

2.02

1.15

0.57

552b

2.1b

397

2.5

1322

0.8

herein

1200

2.33

1.25

0.54

*

*

431

2.8

1437

0.8

herein

1850

2.3

1.35

0.59

369/530c

1.5/2.6c

466

4.0

1552

1.2

herein

1800

2.14

1.28

0.60

400d

3.2d

441

4.1

1471

1.2

Lordan et al. 1998

1028

1.77

1.00

*

304

3.3

343

(3.4)e3.0

1144

0.9

Lordan et al. 1998

975

1.83

1.03

*

390

2.6

355

(2.5)2.8

1183

0.8

Lordan et al. 1998

1084

2.07

1.16

*

435

2.7

402

(2.5)2.7

1338

0.8

Gauldie et al. 1994

2168

2.26

1.27

*

395

3.2

438

(4.1)5.0

1461

1.5

Lipinski 1997

1850

2.2

1.24

*

*

*

427

4.3

1422

1.3

Lipinski 1997

1400

2.42

1.36

*

*

*

469

3.0

1565

0.9

Lipinski 1997

*

2.09

1.18

*

*

*

405

*

1351

*

Lipinski 1997

1770

2.45

1.38

*

*

*

475

3.7

1584

1.1

Lipinski 1997

1180

2.22

1.25

*

*

*

431

2.7

1435

0.8

Jackson et al. 1991

422

0.64f

0.36f

*

153

2.4

124

(2.8)3.4

414

1.0

Lipinski 1991

1680

*

0.15

*

357/536g

0.28/0.42g

*

*

*

*

Brunetti et al. 1998

1625

1.91

0.995h

0.52

321

3.1

343

4.7

1144

1.6

Fernandéz-Nunez & Hernandez-Gonzàléz 1995

2200

*

*

*

548i

*

*

3.9i

*

*

Roeleveld & Lipiński 1991

1680

2.68j

1.58j

0.59

*

*

545

3.1

1816

0.9

et al. 1998

1940

2.13

1.20

*

*

*

414

4.7

1379

1.4

et al. 1998

1680

2.7

1.52

*

*

*

524

3.2

1747

1.0

A — a measured ratio: capella to dorsal edge distance (SFD) / total statolith length (STL), mean = 0.5625 and calculated SFD's = STL*0.5625

B marginal ring interpolation necessary

C marginally unreadable with a complex post-nuclear zone and two variant readings

D marginal rings almost unreadable and interpolation necessary

E mean mantle growth rates in brackets from cited sources, others calculated from table

F axis measured from cited source

G conflicting measurements in cited reference

H pers. comm. (Brunetti 2000)

I cited in Lordan et al. (1998)

J measured from an illustrated figure in source

K number of days derived by dividing SFD by either a mean increment width of 2.9 µm or 0.87 µm with a calculated growth rate column in mm ML d-1

* data unavailable or unable to be calculated


REFERENCES

Aldrich, F.A. 1991: Some aspects of the systematics of and biology of squid of the genus Architeuthis based on a study of specimens from Newfoundland waters. Bulletin of Marine Science, 49(12): 457−481.

Arkhipkin, A.I. 1994: Age, growth and maturation of the squid Enoploteuthis leptura (Oegopsida: Enoploteuthidae) from the central-east Atlantic. Journal of Molluscan Studies, 60: 1−8.

Arkhipkin, A.I. 1997: Age of the micronektonic squid Pterygioteuthis gemmata (Cephalopoda: Pyroteuthidae) from the central-east Atlantic based on statolith growth increments. Journal of Molluscan Studies, 63: 287−290.

Arkhipkin, A.I.; Nekludova, N. 1993: Age, growth and maturation of the loliginid squids Alloteuthis africana and A. subulata on the West African shelf. Journal of the Marine Biological Association of the United Kindom, 73: 949−961.

Arnold, J.M. 1967: Fine structure of the development of the cephalopod lens. Journal of Ultrastructure Research, 17: 527−543.

Bigelow, K.A.; Landgraf, K.C. 1993: Hatch dates and growth of Ommastrephes bartramii paralarvae from Hawaiian waters as determined from statolith analysis. Pp 15−24, in: Recent Advances in Cephalopod Fisheries Biology (Eds: Okutani, T.; O’Dor, R.K.; Kubodera, T.). Tokai University press, Tokyo.

Bizikov, V.A. 1991: A new method of squid age determination using the gladius. In: Proceedings of the International Workshop held in the Instituto di Tecnologia de la Pesca e del Pescato (ITPP-CNR), Mazara del Vallo, Italy, 9−14 October 1989 (eds: Jereb, P; Ragonese, S; Boletzky, S. v.). NTR-ITPP Special Publication 1: 39−51.

Bizikov, V.A.; Arkhipkin, A.I. 1997: Morphology and microstructure of the gladius and statolith from the Boreal Pacific giant squid Moroteuthis robusta (Oegopsida: Onychoteuthidae). Journal of Zoology, 241(3): 475−492.

Bower, J.R. 1996: Estimated paralarval drift and inferred hatching sites for Ommastrephes bartramii (Cephalopoda: Ommastrephidae) near the Hawaiian Archipelago. Fishery Bulletin, U.S., 94(3): 398−411.

Boyle, P.R. 1990: Cephalopod biology in the fisheries context. Fisheries Research, 8: 303−321.

Brothers, E.B.; Mathews, C.P.; Lasker, R. 1976: Daily growth increments in otoliths from larval and adult fishes. Fisheries Bulletin, U.S., 74(1): 1−8.

Brunetti, N.E.; Elena, B.; Rossi, G.R.; Sakai, M.; Pineda, S.E.; Ivanovic, M.L. 1998: Description of an Architeuthis from Argentine waters. South African Journal of Marine Science, 20: 355−361.

Campana, S.E. 1992: Measurement and interpretation of the microstructure of fish otoliths. Pp. 59−71, in: Otolith microstructure examination and analysis (eds: Stevenson, D.K.; Campana, S.E.). Can. Spec. Publ. Fish. Aquat. Scie. 117.

Campana, S.E.; Neilson, J.D. 1985: Microstructure of fish otoliths. Canadian Journal of Fisheries and Aquatic Science, 42: 1014−1032.

Clarke, M.R. 1966: A review of the systematics and ecology of oceanic squids. Advances in Marine Biology, 4: 91−300.

Dawe, E.G.; O’Dor, R.K.; Odense, P.H.; Hurley, G.V. 1985: Validation and application of an ageing technique for short-finned squid (Illex illecebrosus). Journal of the Northwest Atlantic, 6: 107−116.

Dunning, M.C.; Lu, C.C. 1998: Order Teuthoidea. Pp. 515−542, Chapter 13. In: Mollusca: The Southern Synthesis. Fauna of Australia Volume 5 (Eds Beesley, P.L.; Ross, G.J.B.; Wells, A). CSIRO Publishing: Melbourne, Part A xvi 563 pp.

Fernandez-Nunez, M.M.; Hernandez-Gonzàléz, C.L. 1995: Report of a specimen of Architeuthis Steenstrup, 1856 caught in Canarian waters (28°02’N−16°45’W). In: Abstract from the proceedings of the 12th International Malacological Congress, Vigo: 245.

Förch, E.C. 1998: The Marine Fauna of New Zealand: Cephalopoda: Oegopsida: Architeuthidae (giant squid). NIWA Biodiversity Memoir 110: 113pp.

Forsythe, J.W.; van Heukelem, W.F. 1987: Growth. Pp. 135−156, in: Cephalopod Life Cycles, Vol 2 (ed. Boyle, P.R.). Academic Press, Orlando, Fl.

Gauldie, R.W.; West, I.F.; Förch, E.C. 1994: Statocyst, statolith, and age estimation of the giant squid, Architeuthis kirki. The Veliger, 37(1): 93−109.

Hatanaka, H.; Kawahara, S.; Uozumi, Y.; Kasahara, S. 1985: Comparison of life cycles of five ommastrephid squid fished by Japan. Todarodes pacificus, Illex illecebrosus, Illex argentinus, Nototodarus sloani sloani and Nototodarus gouldi. Northwest Atlantic Fisheries Organisation (NAFO) Scientific Council Studies, 9: 59−68.

Hatfield, E.M.C. 1991: Post-recruit growth of the Patagonian squid Loligo gahi (d’Orbigny). Bulletin of Marine cience, 49(12): 349−361.

Hurley, A.C. 1976: Feeding behaviour, food consumption, growth, and resperation of the squid Loligo opalescens raised in the laboratory. Fisheries Bulletin, U.S., 74: 176−182.

Hurley, G.V.; Odense, P.H.; O’Dor, R.K.; Dawe, E.G. 1985: Strontium labelling for verifying daily growth increments in the statolith of the short-finned squid (Illex illecebrosus). Canadian Journal of Fisheries and Aquatic Sciences, 42: 380−383.

Jackson, G.D. 1989: The use of statolith microstructures to analyze life-history events in the small tropical cephalopod Idiosepius pygmaeus. Fishery Bulletin, U.S., 87(2): 265−272.

Jackson, G.D. 1990: Age and growth of the tropical nearshore loliginid squid Sepioteuthis lessoniana determined from statolith growth-ring analysis. Fishery Bulletin, U.S., 88(1): 113−118.Jackson, G.D.; Lu, C.C.; Dunning, M. 1991: Growth rings within the statolith microsculpture of the giant squid Architeuthis. The Veliger, 34(4): 331−334.

Jackson, G.D. 1994: Application and future potential of statolith increment analysis in squids and sepiods. Canadian Journal of Fisheries and aquatic Science, 51: 2612−2625.

Jackson, G.D.; Lu, C.C.; Dunning, M. 1991: Growth rings within the statolith microsculpture of the giant squid Architeuthis. The Veliger, 34(4): 331−334.

Jones, C. 1986: Determining age of larval fish with the otoliths increment technique. Fisheries Bulletin, U.S., 84: 91−103.

Kristenson, T.K. 1980: Periodical growth rings in cephalopod statoliths. Dana, 1: 39−51.

Lipinski, M.R. 1986: Methods for the validation of squid age from statoliths. Journal of the Marine Biological Association of the United Kingdom, 66: 505−526.

Lipinski, M.R. 1991: Scanning electron microscopy (SEM) and chemical treatment. In: Jereb, P.; Ragonese, S.; Boletzky, S. von (eds), Squid age determination using statoliths. Proceedings of the International Workshop held in the Instituto di Tecnologia de la Pesca e del Pescato (ITPP-CNR), Mazara del Vallo, Italy, 9−14 October 1989. NTR-ITPP Special Publication 1: 97−112.

Lipinski, M.R. 1997: Morphology of giant squid Architeuthis statoliths. South African Journal of Marine Science, 18: 299−303.

Lordan, C.; Collins, M.A.; Perales-Raya, C. 1998: Observations on morphology, age and diet of three Architeuthis caught off the west coast of Ireland. Proceedings of the Biological Association of the United Kingdom, 78: 903−917.

Morris, C.C.; Aldrich, F.A. 1985: Statolith length and increment number for age determination of Illex illecebrosus (Lesueur, 1842) (Cephalopoda, Ommastrephidae). NAFO Science Council Studies, 9: 101−106.

Nakamura, Y.; Sakurai, Y. 1991: Validation of daily growth increments in statoliths of Japanese common squid Todarodes pacificus. Nippon Suisan Gakkaishi, 57(11): 2007−2011.Norman, M.D.; Lu, C.C. 1997: Sex in giant squid. Nature, 389: 683−684.

Natsukai, Y.; Nakanose, T.; Oda, K. 1988: Age and growth of the loliginid squid Photololigo edulis (Hoyle, 1885). Journal of Experimental Marine Biology and Ecology, 116: 177−190.

Panella, G. 1971: Fish otoliths: daily growth layers and periodical patterns. Science, 173: 1124−1127.

Patterson, K.R. 1988: Life history of Patagonian squid Loligo gahi and growth parameter estimates using least-squares fits to linear and von Bertalanffy models. Marine Ecology Progress Series, 47: 65−74.

Radke, R.L. 1983: Chemical and structural characteristics of statoliths from the short-finned squid Illex illecebrosus. Marine Biology, 76: 47−54.

Ralston, S. 1985: A novel approach to aging tropical fish. ICLARM Newsletter, 8(1): 14−15.

Raya, C.P.; Fernandez-Nunez, M.M.; Balguerias, E.; Hernandez-Gonzalez, C.L. 1992: Progress towards ageing cuttlefish (Sepia hierredda Rang, 1837) from North West African coast using statoliths. ICES C.M. 1992/K: 33.

Ré, M.E.; Baron, P.J.; Beron, J.C.; Gosztonyi, A.E.; Kuba, L.; Monsalve, M.A.; Sardella, N.H. 1998. A giant squid Architeuthis sp. (Mollusca, Cephalopoda) stranded on the Patagonian shore of Argentina. South African Journal of Marine Science, 20: 109−122.

Roeleveld, M.A.C. & Lipinski, M.R. 1991: The giant squid in southern African waters. Journal of the Zoological Society London, 224: 431−477

Roper, C.F.E.; Boss, K.J. 1982: The giant squid. Scientific American, 246(4): 96−105.

Rosenberg, A.A.; Wilborg, K.F.; Bech, I.M. 1981. Growth of Todarodes sagittatus (Lamarck) (Cephalopod, Ommastrephidae) from the Northeast Atlantic, based on counts of statolith growth rings. Sarsia, 66: 53−57.

Spratt, J.D. 1978: Age and growth of the market squid, Loligo opalescens Berry, in Monterey Bay. Fisheries Bulletin, 169: 35−44.

Toll, R.B. 1990: Cross sectional morphology of the gladius in the family Ommastrephidae (Cephalopoda: Teuthoidea) and its bearing on intrafamilial systematics. Malacologia, 31(2): 313−326.

Turk, P.E.; Hanlon, R.T.; Bradford, L.A.; Yang, W.T. 1986: Aspects of feeding, growth and survival of the European squid Loligo vulgaris Lamarck, 1799, reared through the early growth stages. Vie Milieu, 36(1): 9−13.

Uozumi, Y.; Ohara, H. 1993: Age and growth of Nototodarus sloanii (Cephalopoda: Oegopsida) based on daily increment counts in statoliths. Nihon Suisan Gakkaishi, 59: 1469−1477.

Victor, B.C. 1982: Daily otoliths increments and recruitment in two coral-reef wrasses, Thalassoma bifasciatum and Halichoeres bivattatus. Marine Biology, 71: 203−208.

Volk, E.C.; Mortensen, D.G.; Wertheimer, A.C. 1995: Non-daily otoliths increments and seasonal changes in growth of a pink salmon (Oncorhynchus gorbuscha) population in Auke Bay, Alaska. In: Recent Developments in Fish Otoliths Research (Eds: Secor, D.H.; Deanad, J.M.; Campana, S.E.), University of South Carolina Press: 211−225.

Yang, W.T.; Hixon, R.F.; Turk, P.E.; Krejci, M.E.; Hulet, W.H.; Hanlon, R.T. 1986: Growth, behaviour, and sexual maturation of the market squid, Loligo opalescens, cultured through the life cycle. Fishery Bulletin, 84(4): 771−798.

Yatsu, A.; Mori, J. 2000: Early growth of the Autumn cohort of neon flying squid, Ommastrephes bartramii, in the North Pacific Ocean. Fisheries Research, 45: 189−194.

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