Age, Growth and Otolith Microstructure of the Spotted Lanternfish

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Journal of Marine Science and Engineering

Article Age, Growth and Otolith Microstructure of the Spotted Lanternﬁsh Myctophum punctatum Raﬁnesque 1810

Francesco Longo 1,† , Danilo Malara 2,† , Maria Giulia Stipa 1, Pierpaolo Consoli 1 , Teresa Romeo 3,4, Marilena Sanﬁlippo 1 , Francesco Abbate 5 , Franco Andaloro 1 and Pietro Battaglia 1,*

1 Stazione Zoologica Anton Dohrn, National Institute of Biology, Ecology and Marine Biotechnology, c/o Villa Pace, Contrada Porticatello 29, 98167 Messina, Italy; [email protected] (F.L.); [email protected] (M.G.S.); [email protected] (P.C.); marilena.sanﬁ[email protected] (M.S.); [email protected] (F.A.) 2 Stazione Zoologica Anton Dohrn, National Institute of Biology, Ecology and Marine Biotechnology, Calabrian Researches Centre and Marine Advanced Infrastructures, C.da Torre Spaccata, 87071 Amendolara, CS, Italy; [email protected] 3 Stazione Zoologica Anton Dohrn, National Institute of Biology, Ecology and Marine Biotechnology, Via dei Mille 46, 98057 Milazzo, ME, Italy; [email protected] 4 ISPRA, Italian National Institute for Environmental Protection and Research, BIO-CIT, Via dei Mille 46, 98057 Milazzo, ME, Italy 5 Department of Veterinary Sciences, University of Messina, Polo Universitario Dell’annunziata, 98168 Messina, Italy; [email protected] * Correspondence: [email protected] † These authors equally contributed to the manuscript.

Citation: Longo, F.; Malara, D.; Abstract: This study investigated, for the first time, the age and growth of the spotted lanternfish Stipa, M.G.; Consoli, P.; Romeo, T.; Myctophum punctatum through an analysis of otolith microstructure. A total of 377 individuals were Sanfilippo, M.; Abbate, F.; collected from the Strait of Messina (central Mediterranean Sea), ranging between 20.3 and 73.7 mm Andaloro, F.; Battaglia, P. of standard length. Their length–weight relationship was estimated, and these outputs indicated Age, Growth and Otolith an isometric growth, for all specimens and when males and females were analysed separately. The Microstructure of the Spotted sagittal otoliths were removed from 185 fish, although the microincrement readings were considered Lanternfish Myctophum punctatum valid for only 173 otoliths. Microincrement counts ranged from 32 to 48 (average = 37.6) in the otolith Rafinesque 1810. J. Mar. Sci. Eng. central zone, 30 to 56 (average = 44.3) in the middle zone, and 36 to 384 (average = 165.5) in the 2021, 9, 801. https://doi.org/ 10.3390/jmse9080801 external zone. Overall, total microincrements ranged between 106 and 469. Different growth models (Gompertz, von Bertalanffy and logistic models) were considered, to understand which one fit best Academic Editor: Alexei M. Orlov in describing the growth patterns in M. punctatum. The Gompertz model was then selected as the best-fitting model and its parameters for all individuals were L∞ = 74.79, k = 0.0084 and I = 139.60. Received: 5 May 2021 Accepted: 21 July 2021 Keywords: sagittae; age determination; daily growth; growth model; length–weight relationship; Published: 25 July 2021 Myctophidae; Mediterranean

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- 1. Introduction iations. Lanternfishes (Myctophidae) are an important component of the mesopelagic fauna and include more than 250 small pelagic species [1]. Their key role in the pelagic trophic web is widely recognised thanks to their high biomass [2] and importance in the diet of several top predators [3,4]. Lanternfishes have different life strategies, resulting in various Copyright: © 2021 by the authors. adaptations to deep-sea life and migration patterns. For instance, these species display Licensee MDPI, Basel, Switzerland. different migratory behaviours, which can be resumed in three main categories [5–7]: This article is an open access article (i) strong migrants: species that usually carry out large diel vertical excursions, reaching distributed under the terms and the epipelagic layer at night; (ii) weak migrants: species performing limited vertical conditions of the Creative Commons movements in the water column; (iii) non-migrants: species occurring in the same water Attribution (CC BY) license (https:// layers during both daylight and night. However, the extent of vertical movements in creativecommons.org/licenses/by/ lanternfishes can be influenced by environmental factors, as demonstrated elsewhere [8], 4.0/).

J. Mar. Sci. Eng. 2021, 9, 801. https://doi.org/10.3390/jmse9080801 https://www.mdpi.com/journal/jmse J. Mar. Sci. Eng. 2021, 9, 801 2 of 14

with cyclic migrating patterns in Hygophum spp. from the north and central Atlantic, in relation to the different lunar cycle phases. These differences in migratory behaviour are reflected in the otolith microstructure [8]. For instance, sequences of clear growth increments represent a fast-growth period due to migration in the warmer upper layers; however, when limited vertical excursions occur, less distinguishable increments are laid down, associated with periods of slow growth in deeper and colder waters. Several studies have investigated the depositional periodicity of the growth increments in the microstructure of lanternfish otoliths, and most of them agree that the ring formation occurs on a daily scale, although some fine increments can be laid down sub-daily [2,8–20]. According to the current knowledge, otolith microstructure analysis is useful in investi- gating lanternfish life history traits, since the formation of different otolith regions can be correlated with particular periods of the lifespan, such as the larval zone (LZ), the post-larval zone (PLZ) and the post-metamorphic zone (PMZ). To date, information on the age and growth of lanternfish is still limited to few species, considering the high number of members belonging to the family Myctophidae. Age and growth studies provide useful outputs for the assessment of population dynamics and growth rates and can be applied to better understand fish biology and ecology. This information can also be used for fishery management purposes, given the recent attempts to exploit mesopelagic resources [21]. The aim of this paper is to investigate the age and growth of the spotted lanternfish Myctophum punctatum, Rafinesque 1810, examining the growth patterns in the otolith microstructure and analysing the length–weight relationship. Different growth models were taken into consideration to understand which one fits best when describing the growth patterns in M. punctatum. This species is considered a highly migrant lanternfish, able to perform wide vertical excursions, also reaching the surface at night [7,22–24]. Its population generally displays size stratification in the water column distribution, with a maximum abundance at 700,800 m and with smaller specimens in deeper waters [25]. M. punctatum is quite abundant in the central Mediterranean and plays an important role in the pelagic food web, being predated by several pelagic fish and cephalopods [4,7,22,26]. A better knowledge of the life traits of M. punctatum is essential for understanding the biology and ecology of this species, given that it has already been selected for biotechnological studies due to the interesting anticancer and antibacterial activities of its tissue [27].

2. Materials and Methods 2.1. Sample Collection The specimens examined in this study were found stranded and in good condition (fresh and often alive) along the Sicilian coast of the Strait of Messina (central Mediter- ranean Sea) (Figure1), a location well known for the stranding of mesopelagic and deep fauna mainly due to the peculiar hydrodynamic features of this region [22]. Overall, 377 individual fresh-stranded specimens of M. punctatum were collected before sunrise to avoid weight loss due to dehydration (following [22]), and only undamaged individuals were used for this study.

2.2. Length-Weight Relationship Each individual was measured to the nearest 0.1 mm (standard length, SL) and weighed to the nearest 0.01 g (W). The gender was assessed through the macroscopic observation of gonads and by checking the secondary sexual characteristics (presence of supracaudal gland in males or infracaudal gland in females). The M-SL relationships were assessed for all individuals and for each gender (female and male), using the following equation: W = a (SLb) where W is the body weight, SL is the standard length of the ﬁsh and a is the value of the intercept of the regression line when the function is log-transformed and b is the regression coefﬁcient, i.e., the slope of the log-transformed relation [28–30]. Fish growth J. Mar. Sci. Eng. 2021, 9, 801 3 of 14

is isometric when b = 3; otherwise, it is negative or positive allometric when b < 3 and b > 3, respectively [30]. For each curve (male, female and general), the obtained regression coefficient (b) and the respective 95% confident intervals were compared to the theoretical isometric growth coefficient (b = 3; [31]) through Student’s t-test (One Sample t-test; α = 0.05). In addition, the Welch Two Sample t-test was used to identify differences between male and female M-SL relationships, comparing the regression coefficients bF and bM. The J. Mar. Sci. Eng. 2021, 9, x FOR PEER REVIEW 3 of 16 H0 hypothesis (bF = bM) was accepted when no significant differences (p-value > 0.05) were found [32].

FigureFigure 1.1.Study Study areaarea locatedlocated inin thethe StraitStrait ofof Messina.Messina. 2.3. Otolith Extraction and Preparation 2.2. Length-Weight Relationship The sagittal otoliths were removed from 185 fish, cleaned with water and a small brush Each individual was measured to the nearest 0.1 mm (standard length, SL) and and successively stored dry; each sample was assigned an identification code number. weighed to the nearest 0.01 g (W). The gender was assessed through the macroscopic Prior to otolith preparation, each sagitta was measured to the nearest 0.01 mm, record- observation of gonads and by checking the secondary sexual characteristics (presence of ing the maximum distance from the anterior tip to the posterior edge (maximum length, supracaudal gland in males or infracaudal gland in females). The M-SL relationships were OL) as well as the maximum distance between the dorsal and ventral margins (maxi- assessed for all individuals and for each gender (female and male), using the following mum height, OH), as described elsewhere [33,34]. Measurements were performed using a equation: stereomicroscope (Carl Zeiss, model Discovery V.8, Milano, Italy) coupled with a camera (Axiocam 208 color, ZEISS) and theW ZEN = a 3.1(SL blueb) edition (ZEISS) digital image processing software. where W is the body weight, SL is the standard length of the fish and a is the value of the Otoliths were mounted on slides using Eukitt® mounting medium, and thin sagittal sectionsintercept were of the obtained regression by a grinding/polishing line when the function machine is(Remet log-transformed LS2). and b is the regression coefficient, i.e., the slope of the log-transformed relation [28–30]. Fish growth 2.4.is isometric Otolith Readings, when b = Increments’ 3; otherwise, Interpretation it is negative and or Analysis positive allometric when b < 3 and b > 3, respectivelyOtolith sections [30]. For were each examined curve (male, using afemale light microscope and general), ZEISS the Axioscop2obtained regression coupled withcoefficient a camera (b) and (Axiocam the respective 208 color, 95% ZEISS) confident and intervals the ZEN were 3.1 blue compared edition to (ZEISS) the theoretical digital imageisometric processing growth softwarecoefficient using (b = different3; [31]) through magnifications Student’s to countt-test (One the microincrements. Sample t-test; α = 0.05).Microincrements In addition, the wereWelch counted Two Sample from the t-test core was to theused otolith to identify edge, accordingdifferences to between [10,35], startingmale and from female the M-SL first distinguishablerelationships, comparing increment the after regression the central coefficients primordium bF and and bM. The an- notatingH0 hypothesis the number (bF = bM of) was increments accepted forwhen each no otolithsignificant region: differences central ( (CZ),p-value middle > 0⋅05) (MZ), were andfound external [32]. zones (EZ). According to previous studies [10,11,36], this nomenclature is based on the particular features of the different regions in otolith sections and avoids 2.3. Otolith Extraction and Preparation The sagittal otoliths were removed from 185 fish, cleaned with water and a small brush and successively stored dry; each sample was assigned an identification code number. Prior to otolith preparation, each sagitta was measured to the nearest 0.01 mm, recording the maximum distance from the anterior tip to the posterior edge (maximum length, OL) as well as the maximum distance between the dorsal and ventral margins (maximum height, OH), as described elsewhere [33,34]. Measurements were performed using a stereomicroscope (Carl Zeiss, model Discovery V.8, Milano, Italy) coupled with a

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linking the otolith microstructure to life history traits. Indeed, according to other authors (e.g., [12,14,17], these otolith regions correspond to the larval zone (LZ), post-larval zone (PLZ) and post-metamorphic zone (PMZ), respectively. Several papers (e.g., [14,16,18–20,37]) demonstrate that the microincrements in the otolith structure of lanternﬁsh (Myctophidae) are formed daily; for this reason, we also assumed that the increments observed in the otoliths of M. punctatum are laid down daily. Furthermore, following the methodology of [10], microincrements in each otolith zone (CZ, MZ, EZ) were counted three times. When the differences among these three counts exceeded 5% (i.e., standard error > 5, calculated on the three readings in each otolith zone), the otolith was discarded. Furthermore, seven otoliths were excluded because of unreadable patterns in the middle zone. When the standard error was <5, the readings were considered valid, and the mean value, calculated over the three counts in each otolith, zone was considered. To validate the microincrement readings, some polished sections (n = 10) of otoliths of M. puctatum were etched using a solution of 5% ethylene di-amine tetra acetate (EDTA), pH 7.5, buffered with KOH, for 120 s [38]. After etching, the sections were washed in water (for 3 min), dried and coated with gold. Subsequently, they were examined using a scanning electron microscope (SEM Zeiss EVO MA 10). This control analysis was performed to validate and verify the existence of growth patterns throughout the section and to avoid errors in microstructure interpretation and overestimation in ring counts because of the presence of visual artefacts [38,39].

2.5. Growth Models Length-at-age data of M. puctatum were ﬁtted into three of the most used growth models (von Bertalanffy, Gompertz and logistic models): (−e(−k(t−I))) Gompertz growth model [40]: SL = L∞e (−k (t−t )) von Bertalanffy growth model [41]: SL = L∞ 1 − e 0 −1 (−k(t−I)) Logistic growth model [42,43]: SL = L∞ 1 + e

where SL is the standard length at age t, L∞ is the theoretical asymptotic length, t0 is theoretical age when the body length is equal to 0, k is the growth rate at which SL approaches L∞, whereas I is the age at inflection point. The multi model inference (MMI) approach [12,44–46] was used to compare these different growth models, with the aim of selecting the best one for this species. Comparison was carried out on all data, as well as for both sexes. In this procedure, the definition of starting values is necessary to avoid convergence issues. Therefore, starting values for all model coefficients (L∞, K, t0 or I) were obtained using the “vbStarts” function in the FSA package v.0.8.24 [47], whereas the bootstrapping method, with 999 iterations, was used to calculate standard errors (“nlstools” package v. 1.02; [48]). The best performing model was selected on the basis of the small-sample bias- corrected form of Akaike’s information criterion (AICc), an estimator of prediction error, which assesses the quality of each model, comparing them and representing a tool for model selection [49,50]. The AICc value, delta AICc (∆AICc) and AICc weight [47,49–53] were calculated through the “aictab” function (AICcmodavg package v. 2.2-2; [54]). Generally, the model with lowest AICc value was considered the best. However, when the ∆AICc (difference between AICc of two models) was <2, the model with the highest AICc weight was selected. Finally, residual plots and visual model fit were investigated to validate the selected model. To detect any differences among all best fitting models, the Welch Two Sample t-test (α = 0.05) was used to compare the growth curves’ coefficients (L∞, K, t0 or I). The software packages R (v. 3.6.2) and R-studio (v.1.1.463; [55,56]) were used to perform statistical analysis and to generate models and graphs. J. Mar. Sci. Eng. 2021, 9, x FOR PEER REVIEW 5 of 16

corrected form of Akaike’s information criterion (AICc), an estimator of prediction error, which assesses the quality of each model, comparing them and representing a tool for model selection [49,50]. The AICc value, delta AICc (∆AICc) and AICc weight [47,49–53] were calculated through the “aictab” function (AICcmodavg package v. 2.2-2; [54]). Gen- erally, the model with lowest AICc value was considered the best. However, when the ∆AICc (difference between AICc of two models) was <2, the model with the highest AICc weight was selected. Finally, residual plots and visual model fit were investigated to validate the selected model. To detect any differences among all best fitting models, the Welch Two Sample t-test (α = 0.05) was used to compare the growth curves’ coefficients (L∞, K, t0 or I). The software packages R (v. 3.6.2) and R-studio (v.1.1.463; [55,56]) were used to perform statistical analysis and to generate models and graphs.

3. Results The length frequency distribution of individuals of M. punctatum is given in Figure J. Mar. Sci. Eng. 2021, 9, 801 5 of 14 2. Males (n = 165) were slightly more numerous than females (n = 155), and 57 were not assessed. The size of the individuals ranged between 20.3 and 73.7 mm SL (mean ± standard deviation3. Results = 53.2 ± 10.8), whereas the size ranges of males and females were 31.0–69.4 mm SL (meanThe length± standard frequency deviation distribution = 51.7 ± 7.9) of individuals and 31.6–73.7 of M.mm punctatum SL (meanis ± givenstandard in Figure devia-2. tionMales = 53.2 (n =± 9.5), 165) respectively. were slightly Individuals more numerous were more than abundant females ( nwithin= 155), the and size 57 classes were 45– not 60assessed. mm SL (Figure 2).

FigureFigure 2. 2. LengthLength frequency frequency distribution distribution by by sex sex of of the the studied studied sample sample of of MyctophumMyctophum punctatum punctatum.. The size of the individuals ranged between 20.3 and 73.7 mm SL (mean ± standard Analysis of the length–weight relationship (Figure 3) showed that the growth of M. deviation = 53.2 ± 10.8), whereas the size ranges of males and females were 31.0–69.4 mm punctatum is also isometric (p-value > 0.05) when males and females were analysed sepa- SL (mean ± standard deviation = 51.7 ± 7.9) and 31.6–73.7 mm SL (mean ± standard rately, as demonstrated by the results of Student’s t-test (tall samples = 1.9186, df = 2; tmales = deviation = 53.2 ± 9.5), respectively. Individuals were more abundant within the size −0.1456, df = 2; tfemales = 1.9361, df = 2). Moreover, comparison between the regression coef- classes 45–60 mm SL (Figure2). ficients calculated for M-SL relationships of females and males (bF = 3.1211 and bM = 2.9888, Analysis of the length–weight relationship (Figure3) showed that the growth of respectively) did not show significant differences, and the H0 hypothesis (bF = bM) was ac- M. punctatum is also isometric (p-value > 0.05) when males and females were analysed cepted (t = −1.336, df = 3.8427), supporting the hypothesis of absence of body shape dis- separately, as demonstrated by the results of Student’s t-test (t = 1.9186, df = 2; similarity between sexes. all samples tmales = −0.1456, df = 2; tfemales = 1.9361, df = 2). Moreover, comparison between the regression coefﬁcients calculated for M-SL relationships of females and males (bF = 3.1211 and bM = 2.9888, respectively) did not show signiﬁcant differences, and the H0 hypothesis (bF = bM) was accepted (t = −1.336, df = 3.8427), supporting the hypothesis of absence of body shape dissimilarity between sexes. The observation of microincrements under a light microscope (Figure4) and scanning electron microscope (Figure5) showed that otoliths of M. punctatum had the same features and structure compared to those of other species belonging to Myctophidae. The central zone (CZ) was made up of thin increments laid down around a central primordium (Figures4a and5a). Accessory primordia were sometimes observed after the metamorphic check. The MZ appeared to be darker than the other otolith zones, and its growth increments were larger and organised in thick bands (Figure4a). The growth pattern of EZ was regular, and microincrements were more easily readable Figures4b,c and5b. The microincrement readings were considered valid for 173 otoliths. Microincrement counts ranged from 32 to 48 (mean number of increments = 37.6; mean standard error = 1.69) in the CZ, 30 to 56 (mean number of increments = 44.3; mean standard error = 2.41) in the MZ, 36 to 384 (mean number of increments = 165.5; mean standard error = 2.91) in the EZ. Over- all, total microincrements ranged between 106 and 469 (mean number of increments = 247.4; mean standard error = 3.09). J.J. Mar.Mar. Sci.Sci. Eng.Eng.2021 2021,,9 9,, 801x FOR PEER REVIEW 66 of 1416

FigureFigure 3.3. Length-weightLength-weight relationship relationship for totalfor total individuals individuals (a), males (a), and males females and (femalesb) of Myctophum (b) of Myctophum punctatum. punctatum. Using the starting values reported in Table1, the results of length-at-age analysis suggestThe that observation the Gompertz of microincrements model supported under the data a light (lowest microscope AICc and (Figure Delta AICc4) and values scan- inning Table electron2). microscope (Figure 5) showed that otoliths of M. punctatum had the same features and structure compared to those of other species belonging to Myctophidae. The Tablecentral 1. Startingzone (CZ) values was of made the growth up of modelsthin increments for all datasets laid and down for eacharound gender. a centralL∞ = theprimordium theoretical asymptotic(Figures 4a length, and 5a).t0 = Accessory theoretical ageprimordia when the were body sometimes length is equal observed to 0, k after= the the growth metamor- rate at whichphic check.SL approaches The MZL ∞appearedwhereas I to= thebe agedarker at inﬂection than the point. other otolith zones, and its growth increments were larger and organised in thick bands (Figure 4a). The growth pattern of L∞ k t0/I EZ was regular, and microincrements were more easily readable (Figures 4b,c and 5b). All 75 0.0644 120 Females 70 0.0872 160 Males 75 0.1070 150

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Table 2. Model selection based on AICc results for the general (all data) and gender data relative to the Gompertz, Von Bertalanffy (VBGM) and logistic models.

K AICc Delta_AICc AICcWt Cum. Wt Gompertz 4 912.00 0 0.59 0.59 All VBGM 4 913.07 1.07 0.35 0.94 Logistic 4 916.45 4.45 0.06 1.00 Gompertz 4 419.06 0.00 0.36 0.36 Female VBGM 4 419.23 0.16 0.34 0.70 Logistic 4 419.45 0.38 0.30 1.00 Gompertz 4 347.43 0.00 0.64 0.64 J. Mar. Sci. Eng. 2021, 9, x FOR PEER REVIEWMale Logistic 4 348.60 1.17 0.367 of 16 1.00 VBGM 4 377.70 30.27 0.00 1.00

Figure 4. 4. SagittalSagittal section section of of an an otolith otolith of ofMyctophumMyctophum punctatum punctatum observedobserved by light by light microscope, microscope, showing showing the growth pattern and otolith zones; (a) otolith zones: CZ = central zone; MZ = middle thezone; growth EZ = external pattern zone; and (b otolith,c) microincrement zones; (a) pattern otolith in zones: two different CZ = areas central of the zone; EZ. MZ = middle zone; EZ = external zone; (b,c) microincrement pattern in two different areas of the EZ.

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FigureFigure 5. 5.Sagittal Sagittal section section of of an an otolith otolith of ofMyctophum Myctophum punctatum punctatumobserved observed by scanning by scanning electron electron mi- microscope,croscope, showing showing the the growth growth patternpattern inin thethe central centra zonel zone (CZ) (CZ) and and the the particular particular of growthof growth incre- incrementsments in the in the external external zone zone (EZ) (EZ) (( ((aa,,bb), respectively).

TheThe Gompertz microincrement parameters readings and their were lower considered and upper valid conﬁdent for 173 intervals otoliths. (LCI Microincrement and UCI,counts respectively) ranged from are reported 32 to 48 in Table(mean3, whereasnumber the of growthincrements curves = are 37.6; shown mean in Figurestandard6. error = The1.69) parameters in the CZ, calculated 30 to 56 using(mean the number entire dataset of increments (all data) = were 44.3; as mean follows: standardL∞ = 74.79, error = 2.41) k = 0.0084 and I = 139.60, whereas the parameters estimated by sex were L = 81.45, in the MZ, 36 to 384 (mean number of increments = 165.5; mean standard∞ error = 2.91) in k = 0.0068, I = 143.90 for females and L∞ = 75.03, k = 0.0077, I = 132.00 for males. No signiﬁcantthe EZ. Overall, differences total among microincrements the three growth ranged curves between were observed 106 and (Table 4694 (mean), indicating number of in- thatcrements the growth = 247.4; of M. mean punctatum standardwas similarerror = for 3.09). both sexes. Using the starting values reported in Table 1, the results of length-at-age analysis suggest that the Gompertz model supported the data (lowest AICc and Delta AICc values in Table 2).

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Table 3. Results of the parameters of the best ﬁtting models of all individual, females and males. Information includes L∞, k and I estimates, lower and upper 95% conﬁdential interval (C.I.) and standard errors.

Best Model Parameters Parameters Estimate Lower 95% C.I. Upper 95% C.I. Std. Error

All individuals L∞ 74.79 70.86 79.71 2.28 (Residual standard error: 3.326 on k 0.0084 0.0073 0.0096 0.0006 170 degrees of freedom) I 139.60 133.59 147.48 3.52 Females L∞ 81.45 72.71 99.00 6.31 (Residual standard error: 3.676 on k 0.0068 0.0047 0.0091 0.0012 73 degrees of freedom) I 143.90 130.77 175.08 9.00 Males L∞ 75.03 68.49 87.23 4.56 J. Mar. Sci. Eng. 2021, 9, x FOR PEER REVIEW 10 of 16 (Residual standard error: 2.688 on k 0.0077 0.0054 0.0103 0.0013 68 degrees of freedom) I 132.00 123.64 147.79 5.24

Figure 6. GompertzFigure 6.best-fittingGompertz growth best-ﬁtting curves growth of Myctophum curves punctatum of Myctophum for all punctatum individualsfor and all separated individuals by and sex. separated by sex. Table 4. t-test results of the growth curves’ coefficients (L∞, K, t0 or I) of the age-at-length data between females, males and all individuals. Table 4. t-test results of the growth curves’ coefﬁcients (L∞, K, t0 or I) of the age-at-length data between females, males and all individuals. Compared Parameters of Growth Curves Comparison ComparedL Parameters∞ of Growthk Curves I Comparison L∞ t = 0.7877 kt = −0.4781 I t = 1.0343 Females vs. Malest = 0.7877 df = 3.6094t = −0.4781 df = 3.9573 t = 1.0343 df = 3.0716 Females vs. Males df = 3.6094 p-value = 0.4794df = 3.9573 p-value = 0.6578df = 3.0716p-value = 0.3755 p-value = 0.4794 t = −0.2965p-value = 0.6578 t = 0.4055p-value = 0.3755t = 0.7052 − All vs. Malest = 0.2965 df = 2.8298t = 0.4055 df = 2.7924 t = 0.7052 df = 3.1690 All vs. Males df = 2.8298 df = 2.7924 df = 3.1690 p-value = 0.7872p-value =p 0.7872-value = 0.7142p-value = 0.7142p-value = 0.5290p-value = 0.5290 t = 1.1380 t = 1.1380t = −1.0791 t = −1.0791 t = 0.7055 t = 0.7055 Females vs. AllFemales vs. Alldf = 2.4335 df = 2.4335df = 2.9559 df = 2.9559df = 2.3717 df = 2.3717 p-value = 0.3547p-value =p 0.3547-value = 0.3606p-value = 0.3606p-value = 0.5434p-value = 0.5434

4. Discussion4. Discussion This studyThis investigated, study investigated, for the firstfor the time, first the time, age the and age growth and growth of the of myctophid the myctophid M. M. punctatumpunctatumthrough through the analysis the analysis of the of otolith the otolith microstructure microstructure and assessment and assessment of daily of daily in- increments.crements. AccordingAccording to the results to the of theresults length–weight of the length–weight relationship, relationship, the growth oftheM. growth punctatum of M. puncta- is isometrictum for is both isometric sexes. Thesefor both findings sexes. confirmed These findings the observations confirmed madethe observations in two previous made in two previous studies [33,57], where the isometric relationship between weight and length was observed in 82 and 35 individuals of M. punctatum, respectively, although no differences between sexes were tested. Although other authors have reported a positive or allometric growth in myctophids [33,34,57–60], isometric growth has also been observed in other lanternfish species from the same study area, such as Benthosema glaciale, Ceratoscopelus maderensis, Diaphus holti, Diaphus rafinesquei, Electrona risso, Gonychthys cocco, Lampanyctus pusillus, Notoscopelus elongatus [33,34]. Similar results have been reported for other myctophids by [57] in the western Mediterranean, [11] in the Oman Sea, [60] and in the Atlantic Ocean, although several cases of positive or negative allometric growth have also been observed [12,33,34,57,58,60]. Analysis of otolith microstructure confirmed the general growth pattern observed in other lanternfishes, consisting of three main zones of increment deposition. The first one

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studies [33,57], where the isometric relationship between weight and length was observed in 82 and 35 individuals of M. punctatum, respectively, although no differences between sexes were tested. Although other authors have reported a positive or allometric growth in myctophids [33,34,57–60], isometric growth has also been observed in other lanternfish species from the same study area, such as Benthosema glaciale, Ceratoscopelus maderensis, Diaphus holti, Diaphus rafinesquei, Electrona risso, Gonychthys cocco, Lampanyctus pusillus, Notoscopelus elongatus [33,34]. Similar results have been reported for other myctophids by [57] in the western Mediterranean, [11] in the Oman Sea, [60] and in the Atlantic Ocean, although several cases of positive or negative allometric growth have also been observed [12,33,34,57,58,60]. Analysis of otolith microstructure confirmed the general growth pattern observed in other lanternfishes, consisting of three main zones of increment deposition. The first one is a central zone (CZ), characterised by thin increments surrounding a primordium and usually associated with a larval period [14,17]. A metamorphic check, a dark discontinuity around the nucleus, marks the transition between the CZ and the middle zone (MZ), probably indicating the transition from larva to post-larva [14,17]. Otolith MZ has different features: darker growth increments, larger than the ones laid down in other otolith regions, usually associated with a post-larval period [14,17]. These features have been observed by several authors [9–11,14–17,19,59,61], who agreed that it is usually more difficult to read growth increments in MZ than in other otolith regions. The modification in the otolith microstructure in MZ may be related to an environmental shift due to larval migration towards deep waters [10,59,61,62], to perform transformation, a process which also involves changes in the fish physiology [63,64]. According to [61], the drastic environmental change (from warm upper water layers to cold mesopelagic waters) may contribute to alterations in the regular deposition of growth increments, causing the formation of MZ. Moreover, Reference [10] suggested that otolith microstructure in MZ reflects a period of somatic growth suppression during the non-migratory behaviour of transforming larvae and early juveniles. The last region (external zone, EZ) is characterised by a regular growth pattern with readable microincrements, which became thinner towards the otolith margin. According to previous studies (e.g., [14,17,59]), the deposition of these increments in the otolith structure occurs after the metamorphosis of post-larvae. In general, the growth pattern in the otolith microstructure of M. punctatum is quite regular, which might be related to its particular life traits, since M. punctatum is considered as a highly migrant species, performing wide vertical excursions [7,22,24]. Indeed, Refer- ence [65] observed clearer daily increments in otoliths belonging to species characterised by a well-defined migration pattern. Our reading values for CZ were slightly higher than counts made for otoliths of Benthosema pterotum [11,13,66], Ceratoscopelus warmingii [9] and Lepidophanes guentheri [14]. The average number of microincrements in otolith CZ of M. punctatum was also higher than the values reported by [12,13] for the congeneric species Myctophum asperum and Myctophum spinosum, respectively. Our data are similar to estimations provided for Benthosema suborbitale [14], Diaphus kapalae [16] and Electrona antarctica [17] (Table5). Available data on MZ counts in lanternfish otoliths suggest that the post-larval period has different durations depending on the species and on the geographical area, in relation to different life history traits, migratory behaviour, changes in habitat and diet or environmental parameters (e.g., temperature). Microincrements laid down within this otolith region are few in some species (B. pterotum, D. kalapae, M. asperum), and numerous in Tarletonbeania crenularis [10] (Table5). According to our assessment, the complete transformation from larva to early juvenile in M. punctatum lasts 44.3 days on average. J. Mar. Sci. Eng. 2021, 9, 801 11 of 14

Table 5. Number of increments in the otolith zones in studies regarding age, growth and microstructure of lanternﬁsh species. When information on the increments’ range was lacking, the mean value was provided (*).

Middle Zone Maximum Central Zone Number of SL Range (MZ) or Number of Species (CZ) or Larval References Individuals (mm) Post-Larval Increments in the Zone (LZ) Zone (PLZ) Whole Otolith Benthosemaﬁbulatum 47 15–80 30.8 *–38.4 * - ~410 [13] Benthosemapterotum 98 14–48 28.0 *–31.6 * - ~330 [13] Benthosema pterotum 139 2.6–30.0 11–26 4–11 - [66] Benthosema pterotum 35 16.60–39.49 22–32 8–22 315 [11] Benthosema suborbitale 178 11–33 30–50 13–34 325 [14] Ceratoscopelus 30 5.0–80.7 20–35 20–65 416 [9] warmingii Diaphus diademophilus 2 36–40 29.3 * - 421 [13] Diaphus dumerili 210 12–63 20–40 - 362 [14] Diaphus kapalae 95 11–15 31–48 10–12 77 [16] Electrona antarctica 117 40–103 27–48 38–60 1355 [17] Lampanyctus sp. 7 17–67 26.0 * - 250 [13] Lepidophanes guentheri 280 14–65 20–34 15–40 439 [14] Myctophum asperum 52 58–82 30.4 * 10.3 * 440 [12] Myctophum nitidulum 45 30–79 33–43 20–35 - [36] Present Myctophum punctatum 176 20.3–73.7 32–48 30–56 384 paper Myctophum spinosum 15 67–81 34.0* - 302 [13] Notoscopelus 20 - 35 * 23 * - [58] resplendens Symbolophorus 93 23.0–107.3 30–64 23–61 541 [9] californiensis Symbolophorusevermanni 16 36–86 36.3 * - 249 [13] Tarletonbeania 102 4.6–78.0 51–102 80–139 504 [10] crenularis

Analysis of daily growth by the examination of the sagittal otolith showed that M. punctatum can live more than one year (about 13 months): the maximum number of increments counted in otoliths was equal to 384, within the considered SL range (20.3–73.7 mm). This estimate is coherent with results provided by most studies that focused on the age and growth of lanternfish species through the analysis of the daily deposition of otolith microincrements (Table5). The use of the multi-model inference (MMI) approach [44–46,59] allowed for the selection of the Gompertz model as the best-fitting growth equation to describe the growth of M. punctatum. A similar study on the congeneric species M. asperum from the South China Sea indicated that the von Bertalanffy model was more suitable to define the growth of this lanternfish. However, some authors [18,37] found that the growth in M. asperum best fitted the Gompertz model. The Gompertz model is a sigmoid-shaped growth function which better fits fish with a lower initial growth rate than the von Bertalanffy model. In the case of M. punctatum, this may be related to the fact that juvenile individuals of this species seem to exhibit a different migratory behaviour than adults. Indeed, they usually occur in deeper waters, whereas larger specimens migrate up to the surface [25]. The different environmental conditions at deeper water layers (e.g., lower temperature) may determine a slower growth rate in juveniles/postlarvae. Indeed, transforming larvae and early juvenile stages of many lanternfish species display a non-migratory behaviour, remaining in the mesopelagic environment [10,67]. In our study, the estimated value of the asymptotic maximum body length in females was slightly higher than that in males. In many fish species, males mature earlier, attain- ing a smaller asymptotic size and having higher adult mortality rates than females [68]. Consequently, it is possible that this difference is for this reason, although this explanation needs the support of further studies on the relationship between the somatic growth and J. Mar. Sci. Eng. 2021, 9, 801 12 of 14

reproductive biology of M. punctatum. Moreover, L∞ values for all specimens and sexes were slightly lower than the estimations provided by [12,18,37] for the congeneric species M. asperum. In conclusion, this study analysed the age and growth of M. punctatum through the observation of otolith microstructure, providing data on its lifespan and on the best fitting growth model for this species. These results improve the poor knowledge of this species, although more data should be collected to better understand the influences of environmental parameters on the daily deposition of otolith microincrements and on the duration of larval and postlarval stages. In addition, more information is needed on other aspects of the life history of this lanternfish (maturity, reproduction cycle, vertical migrations, etc.) to fill the knowledge gaps in its biology and ecology.

Author Contributions: Conceptualization, P.B.; methodology, F.L., D.M., F.A. (Francesco Abbate) and P.B.; software, D.M.; validation, F.L., D.M. and P.B.; formal analysis, F.L., D.M., M.G.S., F.A. (Francesco Abbate) and P.B.; investigation, F.L., D.M., M.G.S., F.A. (Francesco Abbate) and P.B.; resources, P.B., F.A. (Franco Andaloro) and T.R.; data curation, F.L., D.M., M.G.S. and P.B.; writing—original draft preparation, P.B., F.L., D.M. and M.S.; writing—review and editing, F.L., D.M., M.G.S., P.C., T.R., M.S., F.A. (Francesco Abbate), F.A. (Franco Andaloro), P.B.; supervision, P.B. All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Conﬂicts of Interest: The authors declare no conﬂict of interest.

References 1. Catul, V.; Gauns, M.; Karuppasamy, P.K. A review on mesopelagic fishes belonging to family Myctophidae. Rev. Fish Biol. Fish. 2011, 21, 339–354. [CrossRef] 2. Gjøsæter, J.; Kawaguchi, K. A review of the world resources of mesopelagic fish. FAO Fish. Tech. Pap. 1980, 193, 1–151. 3. Cherel, Y.; Fontaine, C.; Richard, P.; Labatc, J.-P. Isotopic niches and trophic levels of myctophid fishes and their predators in the Southern Ocean. Limnol. Oceanogr. 2010, 55, 324–332. [CrossRef] 4. Battaglia, P.; Andaloro, F.; Consoli, P.; Esposito, V.; Malara, D.; Musolino, S.; Pedà, C.; Romeo, T. Feeding habits of the Atlantic bluefin tuna, Thunnus thynnus (L. 1758), in the central Mediterranean Sea (Strait of Messina). Helgol. Mar. Res. 2013, 67, 97–107. [CrossRef] 5. Moku, M.; Kawaguchi, K.; Watanabe, H.; Ohno, A. Feeding habits of three dominant myctophid fishes, Diaphus theta, Stenobrachius leucopsarus and S. nannochir, in the subarctic and transitional waters of the western North Pacific. Mar. Ecol. Prog. Ser. 2000, 207, 129–140. [CrossRef] 6. Battaglia, P.; Andaloro, F.; Esposito, V.; Granata, A.; Guglielmo, L.; Guglielmo, R.; Musolino, S.; Romeo, T.; Zagami, G. Diet and trophic ecology of the lanternfish Electrona risso (Cocco 1829) in the Strait of Messina (central Mediterranean Sea) and potential resource utilization from the Deep Scattering Layer (DSL). J. Mar. Syst. 2016, 159, 100–108. [CrossRef] 7. Battaglia, P.; Pagano, L.; Consoli, P.; Esposito, V.; Granata, A.; Guglielmo, L.; Pedá, C.; Romeo, T.; Zagami, G.; Vicchio, T.M. Consumption of mesopelagic prey in the Strait of Messina, an upwelling area of the central Mediterranean Sea: Feeding behaviour of the blue jack mackerel Trachurus picturatus (Bowdich, 1825). Deep Sea Res. Part I Oceanogr. Res. Pap. 2020, 155, 103158. [CrossRef] 8. Linkowski, T.B. Lunar rhythms of vertical migrations coded in otolith microstructure of North Atlantic lanternfishes, genus Hygophum (Myctophidae). Mar. Biol. 1996, 124, 495–508. [CrossRef] 9. Takagi, K.; Yatsu, A.; Moku, M.; Sassa, C. Age and growth of lanternfishes, Symbolophorus californiensis and Ceratoscopelus warmingii (Myctophidae), in the Kuroshio–Oyashio Transition Zone. Ichthyol. Res. 2006, 53, 281–289. [CrossRef] 10. Bystydzieńska,Z.E.; Phillips, A.J.; Linkowski, T.B. Larval stage duration, age and growth of blue lanternfish Tarletonbeania crenularis (Jordan and Gilbert, 1880) derived from otolith microstructure. Environ. Biol. Fishes 2010, 89, 493–503. [CrossRef] 11. Hosseini-Shekarabi, S.P.; Valinassab, T.; Bystydzieńska,Z.; Linkowski, T. Age and growth of Benthosema pterotum (Alcock, 1890)(Myctophidae) in the Oman Sea. J. Appl. Ichthyol. 2015, 31, 51–56. [CrossRef] 12. Wang, Y.; Zhang, J.; Chen, Z.; Jiang, Y.; Xu, S.; Li, Z.; Wang, X.; Ying, Y.; Zhao, X.; Zhou, M. Age and growth of Myctophum asperum in the South China Sea based on otolith microstructure analysis. Deep Sea Res. Part II Top. Stud. Oceanogr. 2019, 167, 121–127. [CrossRef] 13. Gjøsæter, H. Primary growth increments in otoliths of six tropical myctophid species. Biol. Oceanogr. 1987, 4, 359–382. 14. Gartner, J.V., Jr. Life histories of three species of lanternfishes (Pisces: Myctophidae) from the eastern Gulf of Mexico. Mar. Biol. 1991, 111, 11–20. [CrossRef] J. Mar. Sci. Eng. 2021, 9, 801 13 of 14

15. Linkowski, T.B. Otolith microstructure and growth patterns during the early life history of lanternfishes (family Myctophidae). Can. J. Zool. 1991, 69, 1777–1792. [CrossRef] 16. Suthers, I.M. Spatial variability of recent otolith growth and RNA indices in pelagic juvenile Diaphus kapalae (Myctophidae): An effect of flow disturbance near an island? Mar. Freshw. Res. 1996, 47, 273–282. [CrossRef] 17. Greely, T.M.; Gartner, J.V., Jr.; Torres, J.J. Age and growth of Electrona antarctica (Pisces: Myctophidae), the dominant mesopelagic fish of the Southern Ocean. Mar. Biol. 1999, 133, 145–158. [CrossRef] 18. Hayashi, A.; Kawaguchi, K.; Watanabe, H.; Ishida, M. Daily growth increment formation and its lunar periodicity in otoliths of the myctophid fish Myctophum asperum (Pisces: Myctophidae). Fish. Sci. 2001, 67, 811–817. [CrossRef] 19. Moku, M.; Ishimaru, K.; Kawaguchi, K. Growth of larval and juvenile Diaphus theta (Pisces: Myctophidae) in the transitional waters of the western North Pacific. Ichthyol. Res. 2001, 48, 385–390. [CrossRef] 20. Moku, M.; Hayashi, A.; Mori, K.; Watanabe, Y. Validation of daily otolith increment formation in the larval myctophid fish Diaphus slender-type spp. J. Fish Biol. 2005, 67, 1481–1485. [CrossRef] 21. Valinassab, T.; Pierce, G.J.; Johannesson, K. Lantern fish (Benthosema pterotum) resources as a target for commercial exploitation in the Oman Sea. J. Appl. Ichthyol. 2007, 23, 573–577. [CrossRef] 22. Battaglia, P.; Ammendolia, G.; Cavallaro, M.; Consoli, P.; Esposito, V.; Malara, D.; Rao, I.; Romeo, T.; Andaloro, F. Influence of lunar phases, winds and seasonality on the stranding of mesopelagic fish in the Strait of Messina (Central Mediterranean Sea). Mar. Ecol. 2017, 38, e12459. [CrossRef] 23. Olivar, M.P.; Bernal, A.; Molí, B.; Peña, M.; Balbín, R.; Castellón, A.; Miquel, J.; Massutí, E. Vertical distribution, diversity and assemblages of mesopelagic fishes in the western Mediterranean. Deep Sea Res. Part I Oceanogr. Res. Pap. 2012, 62, 53–69. [CrossRef] 24. Di Carlo, B.S.; Costanzo, G.; Fresi, E.; Guglielmo, L.; Ianora, A. Myctophum punctatum. Mar. Ecol. Prog. Ser. 1982, 9, 13–24. 25. Hulley, P.A. Myctophidae; Whitehead, P.J.P., Bauchot, M.-L., Hureau, J.-C., Nielsen, J., Tortonese, E., Eds.; Unesco: Paris, France, 1984; Volume 1. 26. Fossi, M.C.; Pedà, C.; Compa, M.; Tsangaris, C.; Alomar, C.; Claro, F.; Ioakeimidis, C.; Galgani, F.; Hema, T.; Deudero, S. Bioindicators for monitoring marine litter ingestion and its impacts on Mediterranean biodiversity. Environ. Pollut. 2018, 237, 1023–1040. [CrossRef] 27. Lauritano, C.; Martínez, K.A.; Battaglia, P.; Granata, A.; de la Cruz, M.; Cautain, B.; Martìn, J.; Reyes, F.; Ianora, A.; Guglielmo, L. First evidence of anticancer and antimicrobial activity in Mediterranean mesopelagic species. Sci. Rep. 2020, 10, 4929. [CrossRef] [PubMed] 28. Le Cren, E.D. The length-weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis). J. Anim. Ecol. 1951, 20, 201–219. [CrossRef] 29. Froese, R. Cube law, condition factor and weight–length relationships: History, meta-analysis and recommendations. J. Appl. Ichthyol. 2006, 22, 241–253. [CrossRef] 30. Froese, R.; Tsikliras, A.C.; Stergiou, K.I. Editorial note on weight–length relations of fishes. Acta Ichthyol. Piscat. 2011, 41, 261–263. [CrossRef] 31. Snedecor, G.W.; Cochran, W.G. Statistical Methods; Iowa State University Press: Iowa City, IA, USA, 1967. 32. Soliani, L. Manuale di Statistica per la Ricerca e la Professione. 2005. Available online: http//www.dsa.unipr.it/soliani/soliani. html (accessed on 15 June 2021). 33. Battaglia, P.; Malara, D.; Romeo, T.; Andaloro, F. Relationships between otolith size and fish size in some mesopelagic and bathypelagic species from the Mediterranean Sea (Strait of Messina, Italy). Sci. Mar. 2010, 74, 605–612. [CrossRef] 34. Battaglia, P.; Malara, D.; Ammendolia, G.; Romeo, T.; Andaloro, F. Relationships between otolith size and fish length in some mesopelagic teleosts (Myctophidae, Paralepididae, Phosichthyidae and Stomiidae). J. Fish Biol. 2015, 87, 774–782. [CrossRef] 35. Brothers, E.B. Otolith studies. Ontog. Syst. Fishes Spec. Publ. 1984, 1, 50–57. 36. Giragosov, V.; Ovcharov, O.P. Age and growth of the lantern fish Myctophum nitidulum (Myctophidae) from the tropical Atlantic. J. Ichthyol. 1992, 32, 34–42. 37. Hayashi, A.; Watanabe, H.; Ishida, M.; Kawaguchi, K. Growth of Myctophum asperum (Pisces: Myctophidae) in the Kuroshio and transitional waters. Fish. Sci. 2001, 67, 983–984. [CrossRef] 38. Tomás, J.; Panfili, J. Otolith microstructure examination and growth patterns of Vinciguerria nimbaria (Photichthyidae) in the tropical Atlantic Ocean. Fish. Res. 2000, 46, 131–145. [CrossRef] 39. Stevenson, D.K.; Campana, S.E. Otolith microstructure examination and analysis. Can. Spec. Publ. Fish. Aquat. Sci. 1992, 117, 1–126. 40. Gompertz, B. XXIV. On the nature of the function expressive of the law of human mortality, and on a new mode of determining the value of life contingencies. In a letter to Francis Baily, Esq. FRS &c. Philos. Trans. R. Soc. Lond. 1825, 115, 513–583. 41. Von Bertalanffy, L. A quantitative theory of organic growth (inquiries on growth laws. II). Hum. Biol. 1938, 10, 181–213. 42. Ricker, W.E. Linear regressions in fishery research. J. Fish. Board Can. 1973, 30, 409–434. [CrossRef] 43. Ricker, W.E. Computation and interpretation of biological statistics of fish populations. Bull. Fish. Res. Bd. Can. 1975, 191, 1–382. 44. Katsanevakis, S. Modelling fish growth: Model selection, multi-model inference and model selection uncertainty. Fish. Res. 2006, 81, 229–235. [CrossRef] J. Mar. Sci. Eng. 2021, 9, 801 14 of 14

45. Katsanevakis, S.; Maravelias, C.D. Modelling fish growth: Multi-model inference as a better alternative to a priori using von Bertalanffy equation. Fish Fish. 2008, 9, 178–187. [CrossRef] 46. Smart, J.J.; Chin, A.; Tobin, A.J.; Simpfendorfer, C.A. Multimodel approaches in shark and ray growth studies: Strengths, weaknesses and the future. Fish Fish. 2016, 17, 955–971. [CrossRef] 47. Ogle, D.H. Introductory Fisheries Analyses with R; Taylor & Francis Group, CRC Press: Boca Raton, FL, USA, 2016; ISBN 131536252X. 48. Baty, F.; Delignette-Muller, M.L. Nlstools: Tools for Nonlinear Regression Analysis; R Package Version, 2015; Volume 1. Available online: https://cran.r-project.org/web/packages/nlstools/nlstools.pdf (accessed on 15 June 2021). 49. Akaike, H. Information theory as an extension of the maximum likelihood principle. In Second International Symposium on Information Theory; Petrov, B.N., Csaki, F., Eds.; Akademiai Kiado: Budapest, Hungary, 1973; pp. 267–281. 50. Burnham, K.P.; Anderson, D.R. A practical information-theoretic approach. In Model Selection and Multimodel Inference, 2nd ed.; Springer: New York, NY, USA, 2002; Volume 2. 51. Akaike, H. Information measures and model selection. Int. Stat. Inst. 1983, 44, 277–291. 52. Hurvich, C.M.; Tsai, C.-L. Regression and time series model selection in small samples. Biometrika 1989, 76, 297–307. [CrossRef] 53. Mazerolle, M.J.; Linden, D. Model Selection and Multimodel Inference Based on (Q) AIC (c). 2019. Available online: https: //mran.microsoft.com/snapshot/2020-02-28/web/packages/AICcmodavg/AICcmodavg.pdf (accessed on 1 June 2021). 54. Mazerolle, M.J. AICcmodavg: Model Selection and Multimodel Inference Based on (Q) AIC (c). 2020. Available online: https://cran.r-project.org/web/packages/AICcmodavg/AICcmodavg.pdf (accessed on 15 June 2021). 55. Team, R.C. R: A Language and Environment for Statistical Computing (Version 3.1.2); R Foundation for Statistical Computing: Vienna, Austria, 2019. 56. RStudio Team. RStudio: Integrated Development for R; RStudio, Inc.: Boston, MA, USA, 2015. 57. Olivar, M.P.; Molí, B.; Bernal, A. Length-weight relationships of mesopelagic fishes in the north-western Mediterranean. In Proceedings of the Rapport du 40th Congress de la Commission Internationale Pour L’exploration Scientifique de la Mer Mediterranée (CIESM), Marseille, France, 28 October–1 November 2013; Volume 40, p. 528. 58. Sarmiento-Lezcano, A.N.; Triay-Portella, R.; Castro, J.J.; Rubio-Rodríguez, U.; Pajuelo, J.G. Age-based life-history parameters of the mesopelagic fish Notoscopelus resplendens (Richardson, 1845) in the Central Eastern Atlantic. Fish. Res. 2018, 204, 412–423. [CrossRef] 59. Zhang, J.; Wang, C.; Han, J.-R.; Chen, G.-J.; Du, Z.-J. Alteromonas flava sp. nov. and Alteromonas facilis sp. nov., two novel copper tolerating bacteria isolated from a sea cucumber culture pond in China. Syst. Appl. Microbiol. 2019, 42, 217–222. [CrossRef] 60. López-Pérez, C.; Olivar, M.P.; Hulley, P.A.; Tuset, V.M. Length–weight relationships of mesopelagic fishes from the equatorial and tropical Atlantic waters: Influence of environment and body shape. J. Fish Biol. 2020, 96, 1388–1398. [CrossRef] 61. Linkowski, T.B.; Radtke, R.L.; Lenz, P.H. Otolith microstructure, age and growth of two species of Ceratoscopelus (Oosteichthyes: Myctophidae) from the eastern North Atlantic. J. Exp. Mar. Bio. Ecol. 1993, 167, 237–260. [CrossRef] 62. Gjösæter, J. Age, growth, and mortality of the mygtophid fish, Benthosema glaciale (Reinhardt), from Western Norway. Sarsia 1973, 52, 1–14. [CrossRef] 63. Badcock, J.; Merrett, N.R. Midwater fishes in the eastern North Atlantic—I. Vertical distribution and associated biology in 30 N, 23 W, with developmental notes on certain myctophids. Prog. Oceanogr. 1976, 7, 3–58. [CrossRef] 64. Loeb, V.J. Larval fishes in the zooplankton community of the North Pacific Central Gyre. Mar. Biol. 1979, 53, 173–191. [CrossRef] 65. Pannella, G. Growth patterns in fish sagittae. In Skeletal Growth of Aquatic Organisms; Rhoads, D.C., Lutz, R.A., Eds.; Plenum Press: New York, NY, USA, 1980; pp. 519–560. 66. Ozawa, T.; Peñaflor, G.C. Otolith microstructure and early ontogeny of a myctophid species Benthosema pterotum. Nippon. Suisan Gakkaishi 1990, 56, 1987–1995. [CrossRef] 67. Sassa, C.; Kawaguchi, K.; Hirota, Y.; Ishida, M. Distribution depth of the transforming stage larvae of myctophid fishes in the subtropical–tropical waters of the western North Pacific. Deep Sea Res. Part I Oceanogr. Res. Pap. 2007, 54, 2181–2193. [CrossRef] 68. Lester, N.P.; Shuter, B.J.; Abrams, P.A. Interpreting the von Bertalanffy model of somatic growth in fishes: The cost of reproduction. Proc. R. Soc. Lond. Ser. B Biol. Sci. 2004, 271, 1625–1631. [CrossRef][PubMed]